[Gluster-users] Slow write times to gluster disk
Pat Haley
phaley at mit.edu
Fri May 5 14:44:30 UTC 2017
Hi Pranith & Ravi,
A couple of quick questions
We have profile turned on. Are there specific queries we should make
that would help debug our configuration? (The default profile info was
previously sent in
http://lists.gluster.org/pipermail/gluster-users/2017-May/030840.html
but I'm not sure if that is what you were looking for.)
We also started to do a test on serving gluster over NFS. We
rediscovered an issue we previously reported (
http://lists.gluster.org/pipermail/gluster-users/2016-September/028289.html
) in that the NFS mounted version was ignoring the group write
permissions. What specific information would be useful in debugging this?
Thanks
Pat
On 04/14/2017 03:01 AM, Ravishankar N wrote:
> On 04/14/2017 12:20 PM, Pranith Kumar Karampuri wrote:
>>
>>
>> On Sat, Apr 8, 2017 at 10:28 AM, Ravishankar N
>> <ravishankar at redhat.com <mailto:ravishankar at redhat.com>> wrote:
>>
>> Hi Pat,
>>
>> I'm assuming you are using gluster native (fuse mount). If it
>> helps, you could try mounting it via gluster NFS (gnfs) and then
>> see if there is an improvement in speed. Fuse mounts are slower
>> than gnfs mounts but you get the benefit of avoiding a single
>> point of failure. Unlike fuse mounts, if the gluster node
>> containing the gnfs server goes down, all mounts done using that
>> node will fail). For fuse mounts, you could try tweaking the
>> write-behind xlator settings to see if it helps. See the
>> performance.write-behind and performance.write-behind-window-size
>> options in `gluster volume set help`. Of course, even for gnfs
>> mounts, you can achieve fail-over by using CTDB.
>>
>>
>> Ravi,
>> Do you have any data that suggests fuse mounts are slower than
>> gNFS servers?
> I have heard anecdotal evidence time and again on the ML and IRC,
> which is why I wanted to compare it with NFS numbers on his setup.
>>
>> Pat,
>> I see that I am late to the thread, but do you happen to have
>> "profile info" of the workload?
>>
>> You can follow
>> https://gluster.readthedocs.io/en/latest/Administrator%20Guide/Monitoring%20Workload/
>> to get the information.
> Yeah, Let's see if profile info shows up anything interesting.
> -Ravi
>>
>>
>> Thanks,
>> Ravi
>>
>>
>> On 04/08/2017 12:07 AM, Pat Haley wrote:
>>>
>>> Hi,
>>>
>>> We noticed a dramatic slowness when writing to a gluster disk
>>> when compared to writing to an NFS disk. Specifically when using
>>> dd (data duplicator) to write a 4.3 GB file of zeros:
>>>
>>> * on NFS disk (/home): 9.5 Gb/s
>>> * on gluster disk (/gdata): 508 Mb/s
>>>
>>> The gluser disk is 2 bricks joined together, no replication or
>>> anything else. The hardware is (literally) the same:
>>>
>>> * one server with 70 hard disks and a hardware RAID card.
>>> * 4 disks in a RAID-6 group (the NFS disk)
>>> * 32 disks in a RAID-6 group (the max allowed by the card,
>>> /mnt/brick1)
>>> * 32 disks in another RAID-6 group (/mnt/brick2)
>>> * 2 hot spare
>>>
>>> Some additional information and more tests results (after
>>> changing the log level):
>>>
>>> glusterfs 3.7.11 built on Apr 27 2016 14:09:22
>>> CentOS release 6.8 (Final)
>>> RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS-3
>>> 3108 [Invader] (rev 02)
>>>
>>>
>>>
>>> *Create the file to /gdata (gluster)*
>>> [root at mseas-data2 gdata]# dd if=/dev/zero of=/gdata/zero1 bs=1M
>>> count=1000
>>> 1000+0 records in
>>> 1000+0 records out
>>> 1048576000 bytes (1.0 GB) copied, 1.91876 s, *546 MB/s*
>>>
>>> *Create the file to /home (ext4)*
>>> [root at mseas-data2 gdata]# dd if=/dev/zero of=/home/zero1 bs=1M
>>> count=1000
>>> 1000+0 records in
>>> 1000+0 records out
>>> 1048576000 bytes (1.0 GB) copied, 0.686021 s, *1.5 GB/s - *3
>>> times as fast*
>>>
>>>
>>> Copy from /gdata to /gdata (gluster to gluster)
>>> *[root at mseas-data2 gdata]# dd if=/gdata/zero1 of=/gdata/zero2
>>> 2048000+0 records in
>>> 2048000+0 records out
>>> 1048576000 bytes (1.0 GB) copied, 101.052 s, *10.4 MB/s* -
>>> realllyyy slooowww
>>>
>>>
>>> *Copy from /gdata to /gdata* *2nd time *(gluster to gluster)**
>>> [root at mseas-data2 gdata]# dd if=/gdata/zero1 of=/gdata/zero2
>>> 2048000+0 records in
>>> 2048000+0 records out
>>> 1048576000 bytes (1.0 GB) copied, 92.4904 s, *11.3 MB/s* -
>>> realllyyy slooowww again
>>>
>>>
>>>
>>> *Copy from /home to /home (ext4 to ext4)*
>>> [root at mseas-data2 gdata]# dd if=/home/zero1 of=/home/zero2
>>> 2048000+0 records in
>>> 2048000+0 records out
>>> 1048576000 bytes (1.0 GB) copied, 3.53263 s, *297 MB/s *30 times
>>> as fast
>>>
>>>
>>> *Copy from /home to /home (ext4 to ext4)*
>>> [root at mseas-data2 gdata]# dd if=/home/zero1 of=/home/zero3
>>> 2048000+0 records in
>>> 2048000+0 records out
>>> 1048576000 bytes (1.0 GB) copied, 4.1737 s, *251 MB/s* - 30
>>> times as fast
>>>
>>>
>>> As a test, can we copy data directly to the xfs mountpoint
>>> (/mnt/brick1) and bypass gluster?
>>>
>>>
>>> Any help you could give us would be appreciated.
>>>
>>> Thanks
>>>
>>> --
>>>
>>> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>>> Pat Haley Email:phaley at mit.edu <mailto:phaley at mit.edu>
>>> Center for Ocean Engineering Phone: (617) 253-6824
>>> Dept. of Mechanical Engineering Fax: (617) 253-8125
>>> MIT, Room 5-213http://web.mit.edu/phaley/www/
>>> 77 Massachusetts Avenue
>>> Cambridge, MA 02139-4301
>>>
>>> _______________________________________________
>>> Gluster-users mailing list
>>> Gluster-users at gluster.org <mailto:Gluster-users at gluster.org>
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>>> <http://lists.gluster.org/mailman/listinfo/gluster-users>
>>
>> _______________________________________________ Gluster-users
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>>
>> --
>> Pranith
>
--
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley Email: phaley at mit.edu
Center for Ocean Engineering Phone: (617) 253-6824
Dept. of Mechanical Engineering Fax: (617) 253-8125
MIT, Room 5-213 http://web.mit.edu/phaley/www/
77 Massachusetts Avenue
Cambridge, MA 02139-4301
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