[Gluster-users] Slow write times to gluster disk
Pranith Kumar Karampuri
pkarampu at redhat.com
Wed May 17 09:01:04 UTC 2017
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
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