[Gluster-users] Gluster very poor performance when copying small files (1x (2+1) = 3, SSD)

Mon Mar 19 14:42:18 UTC 2018

On 3/19/2018 5:42 AM, Ondrej Valousek wrote:
Removing NFS or NFS Ganesha from the equation, not very impressed on my 
own setup either.  For the writes it's doing, that's alot of CPU usage 
in top. Seems bottle-necked via a single execution core somewhere trying 
to facilitate read / writes to the other bricks.

Writes to the gluster FS from within one of the gluster participating 
bricks:

[root at nfs01 n]# dd if=/dev/zero of=./some-file.bin

393505+0 records in
393505+0 records out
201474560 bytes (201 MB) copied, 50.034 s, 4.0 MB/s

[root at nfs01 n]#

Top results (10 second average)won't go over 32%:

top - 00:49:38 up 21:39,  2 users,  load average: 0.42, 0.24, 0.19
Tasks: 164 total,   1 running, 163 sleeping,   0 stopped,   0 zombie
%Cpu0  : 29.3 us, 24.7 sy,  0.0 ni, 45.1 id,  0.0 wa,  0.0 hi,  0.8 si, 
0.0 st
%Cpu1  : 27.2 us, 24.1 sy,  0.0 ni, 47.2 id,  0.0 wa,  0.0 hi,  1.5 si, 
0.0 st
%Cpu2  : 20.2 us, 13.5 sy,  0.0 ni, 64.1 id,  0.0 wa,  0.0 hi,  2.3 si, 
0.0 st
%Cpu3  : 30.0 us, 16.2 sy,  0.0 ni, 47.5 id,  0.0 wa,  0.0 hi,  6.3 si, 
0.0 st
KiB Mem :  3881708 total,  3207488 free,   346680 used,   327540 buff/cache
KiB Swap:  4063228 total,  4062828 free,      400 used.  3232208 avail Mem

    PID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND
   1319 root      20   0  819036  12928   4036 S 32.3  0.3   1:19.64 
glusterfs
   1310 root      20   0 1232428  25636   4364 S 12.1  0.7   0:41.25 
glusterfsd

Next, the same write but directly to the brick via XFS, which of course 
is faster:

top - 09:45:09 up 1 day,  6:34,  3 users,  load average: 0.61, 1.01, 1.04
Tasks: 171 total,   2 running, 169 sleeping,   0 stopped,   0 zombie
%Cpu0  :  0.6 us,  2.1 sy,  0.0 ni, 82.6 id, 14.5 wa,  0.0 hi,  0.2 si, 
0.0 st
%Cpu1  : 16.7 us, 83.3 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi,  0.0 si, 
0.0 st
%Cpu2  :  0.4 us,  0.9 sy,  0.0 ni, 94.2 id,  4.4 wa,  0.0 hi,  0.0 si, 
0.0 st
%Cpu3  :  1.1 us,  0.6 sy,  0.0 ni, 98.3 id,  0.0 wa,  0.0 hi,  0.0 si, 
0.0 st
KiB Mem :  3881708 total,   501120 free,   230704 used,  3149884 buff/cache
KiB Swap:  4063228 total,  3876896 free,   186332 used.  3343960 avail Mem

   PID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND
14691 root      20   0  107948    608    512 R 25.0  0.0   0:34.29 dd
  1334 root      20   0 2694264  61076   2228 S  2.7  1.6 283:55.96 
ganesha.nfsd

The result of a dd command directly against the brick FS itself is of 
course much better:

[root at nfs01 gv01]# dd if=/dev/zero of=./some-file.bin
5771692+0 records in
5771692+0 records out
2955106304 bytes (3.0 GB) copied, 35.3425 s, 83.6 MB/s

[root at nfs01 gv01]# pwd
/bricks/0/gv01
[root at nfs01 gv01]#

Tried a few tweak options with no effect:

[root at nfs01 glusterfs]# gluster volume info

Volume Name: gv01
Type: Replicate
Volume ID: e5ccc75e-5192-45ac-b410-a34ebd777666
Status: Started
Snapshot Count: 0
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1: nfs01:/bricks/0/gv01
Brick2: nfs02:/bricks/0/gv01
Options Reconfigured:
cluster.server-quorum-type: server
cluster.quorum-type: auto
server.event-threads: 8
client.event-threads: 8
performance.readdir-ahead: on
performance.write-behind-window-size: 8MB
performance.io-thread-count: 16
performance.cache-size: 1GB
nfs.trusted-sync: on
performance.client-io-threads: off
nfs.disable: on
transport.address-family: inet
[root at nfs01 glusterfs]#

That's despite that I can confirm doing 90+ MB/s on my 1Gbe network. 
Thoughts?

-- 
Cheers,
Tom K.
-------------------------------------------------------------------------------------

Living on earth is expensive, but it includes a free trip around the sun.

> Hi,
> As I posted in my previous emails - glusterfs can never match NFS (especially async one) performance of small files/latency. That's given by the design.
> Nothing you can do about it.
> Ondrej
> 
> -----Original Message-----
> From: gluster-users-bounces at gluster.org [mailto:gluster-users-bounces at gluster.org] On Behalf Of Rik Theys
> Sent: Monday, March 19, 2018 10:38 AM
> To: gluster-users at gluster.org; mailinglists at smcleod.net
> Subject: Re: [Gluster-users] Gluster very poor performance when copying small files (1x (2+1) = 3, SSD)
> 
> Hi,
> 
> I've done some similar tests and experience similar performance issues (see my 'gluster for home directories?' thread on the list).
> 
> If I read your mail correctly, you are comparing an NFS mount of the brick disk against a gluster mount (using the fuse client)?
> 
> Which options do you have set on the NFS export (sync or async)?
> 
>  From my tests, I concluded that the issue was not bandwidth but latency.
> Gluster will only return an IO operation once all bricks have confirmed that the data is on disk. If you are using a fuse mount, you might compare with using the 'direct-io-mode=disable' option on the client might help (no experience with this).
> 
> In our tests, I've used NFS-ganesha to serve the gluster volume over NFS. This makes things even worse as NFS-ganesha has no "async" mode, which makes performance terrible.
> 
> If you find a magic knob to make glusterfs fast on small-file workloads, do let me know!
> 
> Regards,
> 
> Rik
> 
> On 03/18/2018 11:13 PM, Sam McLeod wrote:
>> Howdy all,
>>
>> We're experiencing terrible small file performance when copying or
>> moving files on gluster clients.
>>
>> In the example below, Gluster is taking 6mins~ to copy 128MB / 21,000
>> files sideways on a client, doing the same thing on NFS (which I know
>> is a totally different solution etc. etc.) takes approximately 10-15
>> seconds(!).
>>
>> Any advice for tuning the volume or XFS settings would be greatly
>> appreciated.
>>
>> Hopefully I've included enough relevant information below.
>>
>>
>> ## Gluster Client
>>
>> root at gluster-client:/mnt/gluster_perf_test/  # du -sh .
>> 127M    .
>> root at gluster-client:/mnt/gluster_perf_test/  # find . -type f | wc -l
>> 21791
>> root at gluster-client:/mnt/gluster_perf_test/  # du 9584toto9584.txt
>> 4    9584toto9584.txt
>>
>>
>> root at gluster-client:/mnt/gluster_perf_test/  # time cp -a private
>> private_perf_test
>>
>> real    5m51.862s
>> user    0m0.862s
>> sys    0m8.334s
>>
>> root at gluster-client:/mnt/gluster_perf_test/ # time rm -rf
>> private_perf_test/
>>
>> real    0m49.702s
>> user    0m0.087s
>> sys    0m0.958s
>>
>>
>> ## Hosts
>>
>> - 16x Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GHz per Gluster host /
>> client
>> - Storage: iSCSI provisioned (via 10Gbit DAC/Fibre), SSD disk, 50K
>> R/RW 4k IOP/s, 400MB/s per Gluster host
>> - Volumes are replicated across two hosts and one arbiter only host
>> - Networking is 10Gbit DAC/Fibre between Gluster hosts and clients
>> - 18GB DDR4 ECC memory
>>
>> ## Volume Info
>>
>> root at gluster-host-01:~ # gluster pool list UUID          Hostname
>> State ad02970b-e2aa-4ca8-998c-bd10d5970faa  gluster-host-02.fqdn
>> Connected ea116a94-c19e-48db-b108-0be3ae622e2e  gluster-host-03.fqdn
>> Connected
>> 2e855c25-e7ac-4ff6-be85-e8bcc6f45ee4  localhost Connected
>>
>> root at gluster-host-01:~ # gluster volume info uat_storage
>>
>> Volume Name: uat_storage
>> Type: Replicate
>> Volume ID: 7918f1c5-5031-47b8-b054-56f6f0c569a2
>> Status: Started
>> Snapshot Count: 0
>> Number of Bricks: 1 x (2 + 1) = 3
>> Transport-type: tcp
>> Bricks:
>> Brick1: gluster-host-01.fqdn:/mnt/gluster-storage/uat_storage
>> Brick2: gluster-host-02.fqdn:/mnt/gluster-storage/uat_storage
>> Brick3: gluster-host-03.fqdn:/mnt/gluster-storage/uat_storage
>> (arbiter) Options Reconfigured:
>> performance.rda-cache-limit: 256MB
>> network.inode-lru-limit: 50000
>> server.outstanding-rpc-limit: 256
>> performance.client-io-threads: true
>> nfs.disable: on
>> transport.address-family: inet
>> client.event-threads: 8
>> cluster.eager-lock: true
>> cluster.favorite-child-policy: size
>> cluster.lookup-optimize: true
>> cluster.readdir-optimize: true
>> cluster.use-compound-fops: true
>> diagnostics.brick-log-level: ERROR
>> diagnostics.client-log-level: ERROR
>> features.cache-invalidation-timeout: 600
>> features.cache-invalidation: true
>> network.ping-timeout: 15
>> performance.cache-invalidation: true
>> performance.cache-max-file-size: 6MB
>> performance.cache-refresh-timeout: 60
>> performance.cache-size: 1024MB
>> performance.io <http://performance.io>-thread-count: 16
>> performance.md-cache-timeout: 600
>> performance.stat-prefetch: true
>> performance.write-behind-window-size: 256MB
>> server.event-threads: 8
>> transport.listen-backlog: 2048
>>
>> root at gluster-host-01:~ # xfs_info /dev/mapper/gluster-storage-unlocked
>> meta-data=/dev/mapper/gluster-storage-unlocked isize=512    agcount=4,
>> agsize=196607360 blks
>>           =                       sectsz=512   attr=2, projid32bit=1
>>           =                       crc=1        finobt=0 spinodes=0 data
>> =                       bsize=4096   blocks=786429440, imaxpct=5
>>           =                       sunit=0      swidth=0 blks naming
>> =version 2              bsize=8192   ascii-ci=0 ftype=1 log
>> =internal               bsize=4096   blocks=383998, version=2
>>           =                       sectsz=512   sunit=0 blks,
>> lazy-count=1 realtime =none                   extsz=4096   blocks=0,
>> rtextents=0
>>
>>
>> --
>> Sam McLeod (protoporpoise on IRC)
>> https://smcleod.net
>> https://twitter.com/s_mcleod
>>
>> Words are my own opinions and do not necessarily represent those of my
>> employer or partners.
>>
>>
>>
>> _______________________________________________
>> Gluster-users mailing list
>> Gluster-users at gluster.org
>> http://lists.gluster.org/mailman/listinfo/gluster-users
>>
> 
> 
> --
> Rik Theys
> System Engineer
> KU Leuven - Dept. Elektrotechniek (ESAT) Kasteelpark Arenberg 10 bus 2440  - B-3001 Leuven-Heverlee
> +32(0)16/32.11.07
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-- 
Cheers,
Tom K.
-------------------------------------------------------------------------------------

Living on earth is expensive, but it includes a free trip around the sun.