[Gluster-users] Slow write times to gluster disk
Pranith Kumar Karampuri
pkarampu at redhat.com
Tue May 30 16:10:56 UTC 2017
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 <phaley at mit.edu> 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:
>
>
>
> On Tue, May 16, 2017 at 9:20 PM, Pat Haley <phaley at mit.edu> 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_1
>> mseas-data2:/home/gbrick_test_2 transport tcp
>>
>> However we keep getting errors of the form
>>
>> Wrong brick type: transport, use <HOSTNAME>:<export-dir-abs-path>
>>
>> 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:
>>
>>
>>
>> On Thu, May 11, 2017 at 9:32 PM, Pat Haley <phaley at mit.edu> 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:
>>>
>>>
>>>
>>> On Thu, May 11, 2017 at 8:57 PM, Pat Haley <phaley at mit.edu> 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:
>>>>
>>>>
>>>>
>>>> On Thu, May 11, 2017 at 2:48 AM, Pat Haley <phaley at mit.edu> wrote:
>>>>
>>>>>
>>>>> Hi Pranith,
>>>>>
>>>>> Since we are mounting the partitions as the bricks, I tried the dd
>>>>> test writing to <brick-path>/.glusterfs/<file-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:
>>>>>
>>>>>
>>>>>
>>>>> On Wed, May 10, 2017 at 10:15 PM, Pat Haley <phaley at mit.edu> 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)
>>>>>> - gluster w/ fuse mount : 570 Mb/s
>>>>>> - gluster w/ nfs mount: 390 Mb/s
>>>>>> - nfs (no gluster): 1.2 Gb/s
>>>>>> - dd test with oflag=sync (rough average of multiple tests)
>>>>>> - gluster w/ fuse mount: 5 Mb/s
>>>>>> - gluster w/ nfs mount: 200 Mb/s
>>>>>> - 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-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:
>>>>>>
>>>>>> 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 <phaley at mit.edu> 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:
>>>>>>>
>>>>>>> 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 <phaley at mit.edu> wrote:
>>>>>>>
>>>>>>>>
>>>>>>>> Here is what I see now:
>>>>>>>>
>>>>>>>> [root at mseas-data2 ~]# gluster volume info
>>>>>>>>
>>>>>>>> Volume Name: data-volume
>>>>>>>> Type: Distribute
>>>>>>>> Volume ID: c162161e-2a2d-4dac-b015-f31fd89ceb18
>>>>>>>> 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-measurement: on
>>>>>>>> nfs.exports-auth-enable: on
>>>>>>>> diagnostics.brick-sys-log-level: WARNING
>>>>>>>> performance.readdir-ahead: on
>>>>>>>> nfs.disable: on
>>>>>>>> nfs.export-volumes: off
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 05/10/2017 11:44 AM, Pranith Kumar Karampuri wrote:
>>>>>>>>
>>>>>>>> Is this the volume info you have?
>>>>>>>>
>>>>>>>> >* [root at mseas-data2 <http://www.gluster.org/mailman/listinfo/gluster-users> ~]# gluster volume info
>>>>>>>> *>>* Volume Name: data-volume
>>>>>>>> *>* Type: Distribute
>>>>>>>> *>* Volume ID: c162161e-2a2d-4dac-b015-f31fd89ceb18
>>>>>>>> *>* 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?
>>>>>>>>
>>>>>>>> --
>>>>>>>>
>>>>>>>> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>>>>>>>> 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
>>>>>>>>
>>>>>>>> --
>>>>>>> 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
>>>>>>>
>>>>>>> --
>>>>>> 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
>>>>>>
>>>>>> --
>>>>> 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
>>>>>
>>>>> --
>>>> 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
>>>>
>>>> --
>>> 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
>>>
>>> --
>> 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
>>
>>
>
>
> --
> 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
>
>
--
Pranith
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