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Hi All,<br>
<br>
Decided to try another tests of gluster mounted via FUSE vs gluster
mounted via NFS, this time using the software we run in production
(i.e. our ocean model writing a netCDF file).<br>
<br>
gluster mounted via NFS the run took 2.3 hr<br>
<br>
gluster mounted via FUSE: the run took 44.2 hr<br>
<br>
The only problem with using gluster mounted via NFS is that it does
not respect the group write permissions which we need.<br>
<br>
We have an exercise coming up in the a couple of weeks. It seems to
me that in order to improve our write times before then, it would be
good to solve the group write permissions for gluster mounted via
NFS now. We can then revisit gluster mounted via FUSE afterwards.<br>
<br>
What information would you need to help us force gluster mounted via
NFS to respect the group write permissions?<br>
<br>
Thanks<br>
<br>
Pat<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 06/24/2017 01:43 AM, Pranith Kumar
Karampuri wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAOgeEnYe+kyf31Eq_7bh6ZgtC3AE2tc9x52vyrPsBv+2ZQvPcQ@mail.gmail.com">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, Jun 23, 2017 at 9:10 AM,
Pranith Kumar Karampuri <span dir="ltr"><<a
href="mailto:pkarampu@redhat.com" target="_blank"
moz-do-not-send="true">pkarampu@redhat.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote"><span class="gmail-">On Fri,
Jun 23, 2017 at 2:23 AM, Pat Haley <span
dir="ltr"><<a href="mailto:phaley@mit.edu"
target="_blank" moz-do-not-send="true">phaley@mit.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px
0px 0px 0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF"> <br>
Hi,<br>
<br>
Today we experimented with some of the FUSE
options that we found in the list.<br>
<br>
Changing these options had no effect:<br>
<pre>gluster volume set test-volume performance.cache-max-file-siz<wbr>e 2MB
gluster volume set test-volume performance.cache-refresh-time<wbr>out 4
gluster volume set test-volume performance.cache-size 256MB
gluster volume set test-volume performance.write-behind-windo<wbr>w-size 4MB
gluster volume set test-volume performance.write-behind-windo<wbr>w-size 8MB</pre>
</div>
</blockquote>
<div><br>
</div>
</span>
<div>This is a good coincidence, I am meeting with
write-behind maintainer(+Raghavendra G) today for
the same doubt. I think we will have something by
EOD IST. I will update you.<br>
</div>
</div>
</div>
</div>
</blockquote>
<div><br>
</div>
<div>Sorry, forgot to update you. It seems like there is a
bug in Write-behind and Facebook guys sent a patch <a
href="http://review.gluster.org/16079"
moz-do-not-send="true">http://review.gluster.org/16079</a>
to fix the same. But even with that I am not seeing any
improvement. May be I am doing something wrong. Will
update you if I find anything more. <br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div>
<div class="gmail-h5">
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF"> Changing the following
option from its default value made the speed
slower<br>
<pre>gluster volume set test-volume performance.write-behind off (on by default)
</pre>
Changing the following options initially
appeared to give a 10% increase in speed,
but this vanished in subsequent tests (we
think the apparent increase may have been to
a lighter workload on the computer from
other users)<br>
<p><tt>gluster volume set test-volume
performance.stat-prefetch on</tt><tt><br>
</tt><tt> gluster volume set test-volume
client.event-threads 4</tt><tt><br>
</tt><tt> gluster volume set test-volume
server.event-threads 4</tt></p>
<br>
Can anything be gleaned from these
observations? Are there other things we can
try?<br>
<br>
Thanks<span
class="gmail-m_-3105737806683148567HOEnZb"><font
color="#888888"><br>
<br>
Pat</font></span>
<div>
<div
class="gmail-m_-3105737806683148567h5"><br>
<br>
<p><br>
</p>
<div
class="gmail-m_-3105737806683148567m_-1973718441610405686moz-cite-prefix">On
06/20/2017 12:06 PM, Pat Haley wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div
class="gmail-m_-3105737806683148567h5">
<br>
Hi Ben,<br>
<br>
Sorry this took so long, but we had a
real-time forecasting exercise last
week and I could only get to this now.<br>
<br>
Backend Hardware/OS:<br>
<ul>
<li>Much of the information on our
back end system is included at the
top of <a
class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext"
href="http://lists.gluster.org/pipermail/gluster-users/2017-April/030529.html"
target="_blank"
moz-do-not-send="true">http://lists.gluster.org/piper<wbr>mail/gluster-users/2017-April/<wbr>030529.html</a></li>
<li>The specific model of the hard
disks is SeaGate ENTERPRISE
CAPACITY V.4 6TB (ST6000NM0024).
The rated speed is 6Gb/s.</li>
<li>Note: there is one physical
server that hosts both the NFS and
the GlusterFS areas<br>
</li>
</ul>
Latest tests<br>
<br>
I have had time to run the tests for
one of the dd tests you requested to
the underlying XFS FS. The median
rate was 170 MB/s. The dd results and
iostat record are in<br>
<br>
<a
class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext"
href="http://mseas.mit.edu/download/phaley/GlusterUsers/TestXFS/"
target="_blank"
moz-do-not-send="true">http://mseas.mit.edu/download/<wbr>phaley/GlusterUsers/TestXFS/</a><br>
<br>
I'll add tests for the other brick and
to the NFS area later.<br>
<br>
Thanks<br>
<br>
Pat<br>
<br>
<br>
<div
class="gmail-m_-3105737806683148567m_-1973718441610405686moz-cite-prefix">On
06/12/2017 06:06 PM, Ben Turner
wrote:<br>
</div>
<blockquote type="cite">
<pre>Ok you are correct, you have a pure distributed volume. IE no replication overhead. So normally for pure dist I use:
throughput = slowest of disks / NIC * .6-.7
In your case we have:
1200 * .6 = 720
So you are seeing a little less throughput than I would expect in your configuration. What I like to do here is:
-First tell me more about your back end storage, will it sustain 1200 MB / sec? What kind of HW? How many disks? What type and specs are the disks? What kind of RAID are you using?
-Second can you refresh me on your workload? Are you doing reads / writes or both? If both what mix? Since we are using DD I assume you are working iwth large file sequential I/O, is this correct?
-Run some DD tests on the back end XFS FS. I normally have /xfs-mount/gluster-brick, if you have something similar just mkdir on the XFS -> /xfs-mount/my-test-dir. Inside the test dir run:
If you are focusing on a write workload run:
# dd if=/dev/zero of=/xfs-mount/file bs=1024k count=10000 conv=fdatasync
If you are focusing on a read workload run:
# echo 3 > /proc/sys/vm/drop_caches
# dd if=/gluster-mount/file of=/dev/null bs=1024k count=10000
** MAKE SURE TO DROP CACHE IN BETWEEN READS!! **
Run this in a loop similar to how you did in:
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://mseas.mit.edu/download/phaley/GlusterUsers/TestVol/dd_testvol_gluster.txt" target="_blank" moz-do-not-send="true">http://mseas.mit.edu/download/<wbr>phaley/GlusterUsers/TestVol/dd<wbr>_testvol_gluster.txt</a>
Run this on both servers one at a time and if you are running on a SAN then run again on both at the same time. While this is running gather iostat for me:
# iostat -c -m -x 1 > iostat-$(hostname).txt
Lets see how the back end performs on both servers while capturing iostat, then see how the same workload / data looks on gluster.
-Last thing, when you run your kernel NFS tests are you using the same filesystem / storage you are using for the gluster bricks? I want to be sure we have an apples to apples comparison here.
-b
----- Original Message -----
</pre>
<blockquote type="cite">
<pre>From: "Pat Haley" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><phaley@mit.edu></a>
To: "Ben Turner" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:bturner@redhat.com" target="_blank" moz-do-not-send="true"><bturner@redhat.com></a>
Sent: Monday, June 12, 2017 5:18:07 PM
Subject: Re: [Gluster-users] Slow write times to gluster disk
Hi Ben,
Here is the output:
[root@mseas-data2 ~]# gluster volume info
Volume Name: data-volume
Type: Distribute
Volume ID: c162161e-2a2d-4dac-b015-f31fd8<wbr>9ceb18
Status: Started
Number of Bricks: 2
Transport-type: tcp
Bricks:
Brick1: mseas-data2:/mnt/brick1
Brick2: mseas-data2:/mnt/brick2
Options Reconfigured:
nfs.exports-auth-enable: on
diagnostics.brick-sys-log-leve<wbr>l: WARNING
performance.readdir-ahead: on
nfs.disable: on
nfs.export-volumes: off
On 06/12/2017 05:01 PM, Ben Turner wrote:
</pre>
<blockquote type="cite">
<pre>What is the output of gluster v info? That will tell us more about your
config.
-b
----- Original Message -----
</pre>
<blockquote type="cite">
<pre>From: "Pat Haley" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><phaley@mit.edu></a>
To: "Ben Turner" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:bturner@redhat.com" target="_blank" moz-do-not-send="true"><bturner@redhat.com></a>
Sent: Monday, June 12, 2017 4:54:00 PM
Subject: Re: [Gluster-users] Slow write times to gluster disk
Hi Ben,
I guess I'm confused about what you mean by replication. If I look at
the underlying bricks I only ever have a single copy of any file. It
either resides on one brick or the other (directories exist on both
bricks but not files). We are not using gluster for redundancy (or at
least that wasn't our intent). Is that what you meant by replication
or is it something else?
Thanks
Pat
On 06/12/2017 04:28 PM, Ben Turner wrote:
</pre>
<blockquote type="cite">
<pre>----- Original Message -----
</pre>
<blockquote type="cite">
<pre>From: "Pat Haley" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><phaley@mit.edu></a>
To: "Ben Turner" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:bturner@redhat.com" target="_blank" moz-do-not-send="true"><bturner@redhat.com></a>, "Pranith Kumar Karampuri"
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:pkarampu@redhat.com" target="_blank" moz-do-not-send="true"><pkarampu@redhat.com></a>
Cc: "Ravishankar N" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:ravishankar@redhat.com" target="_blank" moz-do-not-send="true"><ravishankar@redhat.com></a>, <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:gluster-users@gluster.org" target="_blank" moz-do-not-send="true">gluster-users@gluster.org</a>,
"Steve Postma" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:SPostma@ztechnet.com" target="_blank" moz-do-not-send="true"><SPostma@ztechnet.com></a>
Sent: Monday, June 12, 2017 2:35:41 PM
Subject: Re: [Gluster-users] Slow write times to gluster disk
Hi Guys,
I was wondering what our next steps should be to solve the slow write
times.
Recently I was debugging a large code and writing a lot of output at
every time step. When I tried writing to our gluster disks, it was
taking over a day to do a single time step whereas if I had the same
program (same hardware, network) write to our nfs disk the time per
time-step was about 45 minutes. What we are shooting for here would be
to have similar times to either gluster of nfs.
</pre>
</blockquote>
<pre>I can see in your test:
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://mseas.mit.edu/download/phaley/GlusterUsers/TestVol/dd_testvol_gluster.txt" target="_blank" moz-do-not-send="true">http://mseas.mit.edu/download/<wbr>phaley/GlusterUsers/TestVol/dd<wbr>_testvol_gluster.txt</a>
You averaged ~600 MB / sec(expected for replica 2 with 10G, {~1200 MB /
sec} / #replicas{2} = 600). Gluster does client side replication so with
replica 2 you will only ever see 1/2 the speed of your slowest part of
the
stack(NW, disk, RAM, CPU). This is usually NW or disk and 600 is
normally
a best case. Now in your output I do see the instances where you went
down to 200 MB / sec. I can only explain this in three ways:
1. You are not using conv=fdatasync and writes are actually going to
page
cache and then being flushed to disk. During the fsync the memory is not
yet available and the disks are busy flushing dirty pages.
2. Your storage RAID group is shared across multiple LUNS(like in a SAN)
and when write times are slow the RAID group is busy serviceing other
LUNs.
3. Gluster bug / config issue / some other unknown unknown.
So I see 2 issues here:
1. NFS does in 45 minutes what gluster can do in 24 hours.
2. Sometimes your throughput drops dramatically.
WRT #1 - have a look at my estimates above. My formula for guestimating
gluster perf is: throughput = NIC throughput or storage(whatever is
slower) / # replicas * overhead(figure .7 or .8). Also the larger the
record size the better for glusterfs mounts, I normally like to be at
LEAST 64k up to 1024k:
# dd if=/dev/zero of=/gluster-mount/file bs=1024k count=10000
conv=fdatasync
WRT #2 - Again, I question your testing and your storage config. Try
using
conv=fdatasync for your DDs, use a larger record size, and make sure that
your back end storage is not causing your slowdowns. Also remember that
with replica 2 you will take ~50% hit on writes because the client uses
50% of its bandwidth to write to one replica and 50% to the other.
-b
</pre>
<blockquote type="cite">
<pre>Thanks
Pat
On 06/02/2017 01:07 AM, Ben Turner wrote:
</pre>
<blockquote type="cite">
<pre>Are you sure using conv=sync is what you want? I normally use
conv=fdatasync, I'll look up the difference between the two and see if
it
affects your test.
-b
----- Original Message -----
</pre>
<blockquote type="cite">
<pre>From: "Pat Haley" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><phaley@mit.edu></a>
To: "Pranith Kumar Karampuri" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:pkarampu@redhat.com" target="_blank" moz-do-not-send="true"><pkarampu@redhat.com></a>
Cc: "Ravishankar N" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:ravishankar@redhat.com" target="_blank" moz-do-not-send="true"><ravishankar@redhat.com></a>,
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:gluster-users@gluster.org" target="_blank" moz-do-not-send="true">gluster-users@gluster.org</a>,
"Steve Postma" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:SPostma@ztechnet.com" target="_blank" moz-do-not-send="true"><SPostma@ztechnet.com></a>, "Ben
Turner" <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:bturner@redhat.com" target="_blank" moz-do-not-send="true"><bturner@redhat.com></a>
Sent: Tuesday, May 30, 2017 9:40:34 PM
Subject: Re: [Gluster-users] Slow write times to gluster disk
Hi Pranith,
The "dd" command was:
dd if=/dev/zero count=4096 bs=1048576 of=zeros.txt conv=sync
There were 2 instances where dd reported 22 seconds. The output from
the
dd tests are in
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://mseas.mit.edu/download/phaley/GlusterUsers/TestVol/dd_testvol_gluster.txt" target="_blank" moz-do-not-send="true">http://mseas.mit.edu/download/<wbr>phaley/GlusterUsers/TestVol/dd<wbr>_testvol_gluster.txt</a>
Pat
On 05/30/2017 09:27 PM, Pranith Kumar Karampuri wrote:
</pre>
<blockquote
type="cite">
<pre>Pat,
What is the command you used? As per the following output,
it
seems like at least one write operation took 16 seconds. Which is
really bad.
96.39 1165.10 us 89.00 us*16487014.00 us*
393212
WRITE
On Tue, May 30, 2017 at 10:36 PM, Pat Haley <<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>> wrote:
Hi Pranith,
I ran the same 'dd' test both in the gluster test volume and
in
the .glusterfs directory of each brick. The median results
(12
dd
trials in each test) are similar to before
* gluster test volume: 586.5 MB/s
* bricks (in .glusterfs): 1.4 GB/s
The profile for the gluster test-volume is in
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://mseas.mit.edu/download/phaley/GlusterUsers/TestVol/profile_testvol_gluster.txt" target="_blank" moz-do-not-send="true">http://mseas.mit.edu/download/<wbr>phaley/GlusterUsers/TestVol/pr<wbr>ofile_testvol_gluster.txt</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="http://mseas.mit.edu/download/phaley/GlusterUsers/TestVol/profile_testvol_gluster.txt" target="_blank" moz-do-not-send="true"><http://mseas.mit.edu/download<wbr>/phaley/GlusterUsers/TestVol/<wbr>profile_testvol_gluster.txt></a>
Thanks
Pat
On 05/30/2017 12:10 PM, Pranith Kumar Karampuri wrote:
</pre>
<blockquote
type="cite">
<pre> Let's start with the same 'dd' test we were testing with to
see,
what the numbers are. Please provide profile numbers for the
same. From there on we will start tuning the volume to see
what
we can do.
On Tue, May 30, 2017 at 9:16 PM, Pat Haley <<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>> wrote:
Hi Pranith,
Thanks for the tip. We now have the gluster volume
mounted
under /home. What tests do you recommend we run?
Thanks
Pat
On 05/17/2017 05:01 AM, Pranith Kumar Karampuri wrote:
</pre>
<blockquote
type="cite">
<pre> On Tue, May 16, 2017 at 9:20 PM, Pat Haley
<<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>> wrote:
Hi Pranith,
Sorry for the delay. I never saw received your
reply
(but I did receive Ben Turner's follow-up to your
reply). So we tried to create a gluster volume
under
/home using different variations of
gluster volume create test-volume
mseas-data2:/home/gbrick_test_<wbr>1
mseas-data2:/home/gbrick_test_<wbr>2 transport tcp
However we keep getting errors of the form
Wrong brick type: transport, use
<HOSTNAME>:<export-dir-abs-pat<wbr>h>
Any thoughts on what we're doing wrong?
You should give transport tcp at the beginning I think.
Anyways, transport tcp is the default, so no need to
specify
so remove those two words from the CLI.
Also do you have a list of the test we should be
running
once we get this volume created? Given the
time-zone
difference it might help if we can run a small
battery
of tests and post the results rather than
test-post-new
test-post... .
This is the first time I am doing performance analysis
on
users as far as I remember. In our team there are
separate
engineers who do these tests. Ben who replied earlier is
one
such engineer.
Ben,
Have any suggestions?
Thanks
Pat
On 05/11/2017 12:06 PM, Pranith Kumar Karampuri
wrote:
</pre>
<blockquote
type="cite">
<pre> On Thu, May 11, 2017 at 9:32 PM, Pat Haley
<<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a> <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>> wrote:
Hi Pranith,
The /home partition is mounted as ext4
/home ext4 defaults,usrquota,grpquota 1 2
The brick partitions are mounted ax xfs
/mnt/brick1 xfs defaults 0 0
/mnt/brick2 xfs defaults 0 0
Will this cause a problem with creating a
volume
under /home?
I don't think the bottleneck is disk. You can do
the
same tests you did on your new volume to confirm?
Pat
On 05/11/2017 11:32 AM, Pranith Kumar Karampuri
wrote:
</pre>
<blockquote
type="cite">
<pre> On Thu, May 11, 2017 at 8:57 PM, Pat Haley
<<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a> <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>>
wrote:
Hi Pranith,
Unfortunately, we don't have similar
hardware
for a small scale test. All we have is
our
production hardware.
You said something about /home partition which
has
lesser disks, we can create plain distribute
volume inside one of those directories. After
we
are done, we can remove the setup. What do you
say?
Pat
On 05/11/2017 07:05 AM, Pranith Kumar
Karampuri wrote:
</pre>
<blockquote
type="cite">
<pre> On Thu, May 11, 2017 at 2:48 AM, Pat
Haley
<<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a> <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>>
wrote:
Hi Pranith,
Since we are mounting the partitions
as
the bricks, I tried the dd test
writing
to
<brick-path>/.glusterfs/<file-<wbr>to-be-removed-after-test>.
The results without oflag=sync were
1.6
Gb/s (faster than gluster but not as
fast
as I was expecting given the 1.2 Gb/s
to
the no-gluster area w/ fewer disks).
Okay, then 1.6Gb/s is what we need to
target
for, considering your volume is just
distribute. Is there any way you can do
tests
on similar hardware but at a small scale?
Just so we can run the workload to learn
more
about the bottlenecks in the system? We
can
probably try to get the speed to 1.2Gb/s
on
your /home partition you were telling me
yesterday. Let me know if that is
something
you are okay to do.
Pat
On 05/10/2017 01:27 PM, Pranith Kumar
Karampuri wrote:
</pre>
<blockquote
type="cite">
<pre> On Wed, May 10, 2017 at 10:15 PM,
Pat
Haley <<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>> wrote:
Hi Pranith,
Not entirely sure (this isn't my
area of expertise). I'll run
your
answer by some other people who
are
more familiar with this.
I am also uncertain about how to
interpret the results when we
also
add the dd tests writing to the
/home area (no gluster, still on
the
same machine)
* dd test without oflag=sync
(rough average of multiple
tests)
o gluster w/ fuse mount :
570
Mb/s
o gluster w/ nfs mount:
390
Mb/s
o nfs (no gluster): 1.2
Gb/s
* dd test with oflag=sync
(rough
average of multiple tests)
o gluster w/ fuse mount:
5
Mb/s
o gluster w/ nfs mount:
200
Mb/s
o nfs (no gluster): 20
Mb/s
Given that the non-gluster area
is
a
RAID-6 of 4 disks while each
brick
of the gluster area is a RAID-6
of
32 disks, I would naively expect
the
writes to the gluster area to be
roughly 8x faster than to the
non-gluster.
I think a better test is to try and
write to a file using nfs without
any
gluster to a location that is not
inside
the brick but someother location
that
is
on same disk(s). If you are mounting
the
partition as the brick, then we can
write to a file inside .glusterfs
directory, something like
<brick-path>/.glusterfs/<file-<wbr>to-be-removed-after-test>.
I still think we have a speed
issue,
I can't tell if fuse vs nfs is
part
of the problem.
I got interested in the post because
I
read that fuse speed is lesser than
nfs
speed which is counter-intuitive to
my
understanding. So wanted
clarifications.
Now that I got my clarifications
where
fuse outperformed nfs without sync,
we
can resume testing as described
above
and try to find what it is. Based on
your email-id I am guessing you are
from
Boston and I am from Bangalore so if
you
are okay with doing this debugging
for
multiple days because of timezones,
I
will be happy to help. Please be a
bit
patient with me, I am under a
release
crunch but I am very curious with
the
problem you posted.
Was there anything useful in the
profiles?
Unfortunately profiles didn't help
me
much, I think we are collecting the
profiles from an active volume, so
it
has a lot of information that is not
pertaining to dd so it is difficult
to
find the contributions of dd. So I
went
through your post again and found
something I didn't pay much
attention
to
earlier i.e. oflag=sync, so did my
own
tests on my setup with FUSE so sent
that
reply.
Pat
On 05/10/2017 12:15 PM, Pranith
Kumar Karampuri wrote:
</pre>
<blockquote
type="cite">
<pre> Okay good. At least this
validates
my doubts. Handling O_SYNC in
gluster NFS and fuse is a bit
different.
When application opens a file
with
O_SYNC on fuse mount then each
write syscall has to be written
to
disk as part of the syscall
where
as in case of NFS, there is no
concept of open. NFS performs
write
though a handle saying it needs
to
be a synchronous write, so
write()
syscall is performed first then
it
performs fsync(). so an write
on
an
fd with O_SYNC becomes
write+fsync.
I am suspecting that when
multiple
threads do this write+fsync()
operation on the same file,
multiple writes are batched
together to be written do disk
so
the throughput on the disk is
increasing is my guess.
Does it answer your doubts?
On Wed, May 10, 2017 at 9:35
PM,
Pat Haley <<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>> wrote:
Without the oflag=sync and
only
a single test of each, the
FUSE
is going faster than NFS:
FUSE:
mseas-data2(dri_nascar)% dd
if=/dev/zero count=4096
bs=1048576 of=zeros.txt
conv=sync
4096+0 records in
4096+0 records out
4294967296 bytes (4.3 GB)
copied, 7.46961 s, 575 MB/s
NFS
mseas-data2(HYCOM)% dd
if=/dev/zero count=4096
bs=1048576 of=zeros.txt
conv=sync
4096+0 records in
4096+0 records out
4294967296 bytes (4.3 GB)
copied, 11.4264 s, 376 MB/s
On 05/10/2017 11:53 AM,
Pranith
Kumar Karampuri wrote:
</pre>
<blockquote
type="cite">
<pre> Could you let me know the
speed without oflag=sync
on
both the mounts? No need
to
collect profiles.
On Wed, May 10, 2017 at
9:17
PM, Pat Haley
<<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>>
wrote:
Here is what I see
now:
[root@mseas-data2 ~]#
gluster volume info
Volume Name:
data-volume
Type: Distribute
Volume ID:
c162161e-2a2d-4dac-b015-f31fd8<wbr>9ceb18
Status: Started
Number of Bricks: 2
Transport-type: tcp
Bricks:
Brick1:
mseas-data2:/mnt/brick1
Brick2:
mseas-data2:/mnt/brick2
Options Reconfigured:
diagnostics.count-fop-hits:
on
diagnostics.latency-measuremen<wbr>t:
on
nfs.exports-auth-enable:
on
diagnostics.brick-sys-log-leve<wbr>l:
WARNING
performance.readdir-ahead:
on
nfs.disable: on
nfs.export-volumes:
off
On 05/10/2017 11:44
AM,
Pranith Kumar
Karampuri
wrote:
</pre>
<blockquote
type="cite">
<pre> Is this the volume
info
you have?
>/[root at
>mseas-data2
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="http://www.gluster.org/mailman/listinfo/gluster-users" target="_blank" moz-do-not-send="true"><http://www.gluster.org/mailma<wbr>n/listinfo/gluster-users></a>
~]# gluster volume
info
/>//>/Volume Name:
data-volume />/Type:
Distribute />/Volume
ID:
c162161e-2a2d-4dac-b015-f31fd8<wbr>9ceb18
/>/Status: Started
/>/Number
of Bricks: 2
/>/Transport-type:
tcp
/>/Bricks: />/Brick1:
mseas-data2:/mnt/brick1
/>/Brick2:
mseas-data2:/mnt/brick2
/>/Options
Reconfigured:
/>/performance.readdir-ahead:
on />/nfs.disable: on
/>/nfs.export-volumes:
off
/
I copied this from
old
thread from 2016.
This
is
distribute volume.
Did
you change any of the
options in between?
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean
Engineering
Phone: (617) 253-6824
Dept. of Mechanical
Engineering
Fax: (617) 253-8125
MIT, Room
5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts
Avenue
Cambridge, MA
02139-4301
--
Pranith
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean
Engineering
Phone: (617) 253-6824
Dept. of Mechanical
Engineering
Fax: (617) 253-8125
MIT, Room
5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
--
Pranith
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean Engineering
Phone:
(617) 253-6824
Dept. of Mechanical Engineering
Fax:
(617) 253-8125
MIT, Room
5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
--
Pranith
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean Engineering
Phone:
(617) 253-6824
Dept. of Mechanical Engineering
Fax:
(617) 253-8125
MIT, Room
5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
--
Pranith
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean Engineering Phone:
(617)
253-6824
Dept. of Mechanical Engineering Fax:
(617)
253-8125
MIT, Room
5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
--
Pranith
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean Engineering Phone:
(617)
253-6824
Dept. of Mechanical Engineering Fax:
(617)
253-8125
MIT, Room 5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
--
Pranith
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean Engineering Phone: (617)
253-6824
Dept. of Mechanical Engineering Fax: (617)
253-8125
MIT, Room 5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
--
Pranith
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
--
Pranith
</pre>
</blockquote>
<pre> --
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:Email:phaley@mit.edu" target="_blank" moz-do-not-send="true">Email:phaley@mit.edu</a>
<a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-rfc2396E" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true"><mailto:phaley@mit.edu></a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213<a href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley<wbr>/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
--
Pranith
</pre>
</blockquote>
<pre>--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley Email: <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
</pre>
</blockquote>
</blockquote>
<pre>--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley Email: <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
</pre>
</blockquote>
</blockquote>
<pre>--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley Email: <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
</pre>
</blockquote>
</blockquote>
<pre>--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley Email: <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
</pre>
</blockquote>
</blockquote>
<br>
<pre class="gmail-m_-3105737806683148567m_-1973718441610405686moz-signature" cols="72">--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley Email: <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
</pre>
<br>
<fieldset
class="gmail-m_-3105737806683148567m_-1973718441610405686mimeAttachmentHeader"></fieldset>
<br>
</div>
</div>
<span>
<pre>______________________________<wbr>_________________
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<span>
<pre class="gmail-m_-3105737806683148567m_-1973718441610405686moz-signature" cols="72">--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<wbr>-=-=-
Pat Haley Email: <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-abbreviated" href="mailto:phaley@mit.edu" target="_blank" moz-do-not-send="true">phaley@mit.edu</a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 <a class="gmail-m_-3105737806683148567m_-1973718441610405686moz-txt-link-freetext" href="http://web.mit.edu/phaley/www/" target="_blank" moz-do-not-send="true">http://web.mit.edu/phaley/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
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<div dir="ltr">Pranith<br>
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Pat Haley Email: <a class="moz-txt-link-abbreviated" href="mailto:phaley@mit.edu">phaley@mit.edu</a>
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 <a class="moz-txt-link-freetext" href="http://web.mit.edu/phaley/www/">http://web.mit.edu/phaley/www/</a>
77 Massachusetts Avenue
Cambridge, MA 02139-4301
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