[ovirt-users] Re: Super Low VM disk IO via Shared Storage

Hi oVirt gurus, Thank s to Tony, who pointed me into discovery process, the performance of the IO seems greatly dependent on the flags. [root@lgu215 ~]# dd if=/dev/zero of=/tmp/test1.img bs=512 count=100000 100000+0 records in 100000+0 records out 51200000 bytes (51 MB) copied, 0.108962 s, *470 MB/s* [root@lgu215 ~]# dd if=/dev/zero of=/tmp/test1.img bs=512 count=100000 *oflag=dsync* 100000+0 records in 100000+0 records out 51200000 bytes (51 MB) copied, 322.314 s, *159 kB/s* Dsync flag tells dd to ignore all buffers, cache except certain kernel buffers and write data physically to the disc, before writing further. According to number of sites I looked at, this is the way to test Server Latency in regards to IO operations. Difference in performance is huge, as you can see (below I have added results from tests with 4k and 8k block) Still, certain software component we run tests with writes data in this/similar way, which is why I got this complaint in the first place. Here is my current NFS mount settings: rw,relatime,vers=4.0,rsize=65536,wsize=65536,namlen=255,soft,nosharecache,proto=tcp,timeo=600,retrans=6,sec=sys,clientaddr=172.17.28.11,local_lock=none,addr=172.17.28.5 *If you have any suggestions on possible NFS tuning options, to try to increase performance, I would highly appreciate it.*

existing/used storage?*

Test results with 4096 and 8192 byte size. [root@lgu215 ~]# dd if=/dev/zero of=/tmp/test1.img bs=4096 count=100000 100000+0 records in 100000+0 records out 409600000 bytes (410 MB) copied, 1.49831 s, *273 MB/s* [root@lgu215-admin ~]# dd if=/dev/zero of=/tmp/test1.img bs=4096 count=100000 *oflag=dsync* 100000+0 records in 100000+0 records out 409600000 bytes (410 MB) copied, 349.041 s, *1.2 MB/s* [root@lgu215 ~]# dd if=/dev/zero of=/tmp/test1.img bs=8192 count=100000 100000+0 records in 100000+0 records out 819200000 bytes (819 MB) copied, 11.6553 s, *70.3 MB/s* [root@lgu215-admin ~]# dd if=/dev/zero of=/tmp/test1.img bs=8192 count=100000 *oflag=dsync* 100000+0 records in 100000+0 records out 819200000 bytes (819 MB) copied, 393.035 s, *2.1 MB/s* *From: *"Vrgotic, Marko" <M.Vrgotic(a)activevideo.com&gt; *Date: *Thursday, 26 September 2019 at 09:51 *To: *Amit Bawer <abawer(a)redhat.com&gt; *Cc: *Tony Brian Albers <tba(a)kb.dk&gt;, &quot;hunter86_bg(a)yahoo.com&quot; < hunter86_bg(a)yahoo.com&gt;, &quot;users(a)ovirt.org&quot; <users(a)ovirt.org&gt; *Subject: *Re: [ovirt-users] Re: Super Low VM disk IO via Shared Storage Dear all, I very much appreciate all help and suggestions so far. Today I will send the test results and current mount settings for NFS4. Our production setup is using Netapp based NFS server. I am surprised with results from Tony’s test. We also have one setup with Gluster based NFS, and I will run tests on those as well. Sent from my iPhone On 25 Sep 2019, at 14:18, Amit Bawer <abawer(a)redhat.com&gt; wrote: On Wed, Sep 25, 2019 at 2:44 PM Tony Brian Albers <tba(a)kb.dk&gt; wrote: Guys, Just for info, this is what I'm getting on a VM that is on shared storage via NFSv3: --------------------------snip---------------------- [root@proj-000 ~]# time dd if=/dev/zero of=testfile bs=4096 count=1000000 1000000+0 records in 1000000+0 records out 4096000000 bytes (4.1 GB) copied, 18.0984 s, 226 MB/s real 0m18.171s user 0m1.077s sys 0m4.303s [root@proj-000 ~]# --------------------------snip---------------------- my /etc/exports: /data/ovirt *(rw,sync,no_subtree_check,all_squash,anonuid=36,anongid=36) and output from 'mount' on one of the hosts: sto-001.kac.lokalnet:/data/ovirt on /rhev/data-center/mnt/sto- 001.kac.lokalnet:_data_ovirt type nfs (rw,relatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,soft,nolock, nosharecache,proto=tcp,timeo=600,retrans=6,sec=sys,mountaddr=172.16.216 .41,mountvers=3,mountport=20048,mountproto=udp,local_lock=all,addr=172. 16.216.41) Worth to compare mount options with the slow shared NFSv4 mount. Window size tuning can be found at bottom of [1], although its relating to NFSv3, it could be relevant to v4 as well. [1] https://www.ovirt.org/develop/troubleshooting-nfs-storage-issues.html connected via single 10gbit ethernet. Storage on NFS server is 8 x 4TB SATA disks in RAID10. NFS server is running CentOS 7.6. Maybe you can get some inspiration from this. /tony On Wed, 2019-09-25 at 09:59 +0000, Vrgotic, Marko wrote: > Dear Strahil, Amit, > > Thank you for the suggestion. > Test result with block size 4096: > Network storage: > avshared: > [root@mpoludctest4udc-1 ~]# dd if=/dev/zero of=/tmp/test2.img bs=4096 > count=100000 oflag=dsync > 100000+0 records in > 100000+0 records out > 409600000 bytes (410 MB) copied, 275.522 s, 1.5 MB/s > > Local storage: > > avlocal2: > [root@mpollocalcheck22 ~]# dd if=/dev/zero of=/tmp/test2.img bs=4096 > count=100000 oflag=dsync > 100000+0 records in > 100000+0 records out > 409600000 bytes (410 MB) copied, 53.093 s, 7.7 MB/s > 10:38 > avlocal3: > [root@mpollocalcheck3 ~]# dd if=/dev/zero of=/tmp/test2.img bs=4096 > count=100000 oflag=dsync > 100000+0 records in > 100000+0 records out > 409600000 bytes (410 MB) copied, 46.0392 s, 8.9 MB/s > > As Amit suggested, I am also going to execute same tests on the > BareMetals and between BareMetal and NFS to compare results. > > > — — — > Met vriendelijke groet / Kind regards, > > Marko Vrgotic > > > > > From: Strahil <hunter86_bg(a)yahoo.com&gt; > Date: Tuesday, 24 September 2019 at 19:10 > To: "Vrgotic, Marko" <M.Vrgotic(a)activevideo.com&gt;, Amit <abawer@redhat > .com> > Cc: users <users(a)ovirt.org&gt; > Subject: Re: [ovirt-users] Re: Super Low VM disk IO via Shared > Storage > > Why don't you try with 4096 ? > Most block devices have a blcok size of 4096 and anything bellow is > slowing them down. > Best Regards, > Strahil Nikolov > On Sep 24, 2019 17:40, Amit Bawer <abawer(a)redhat.com&gt; wrote: > have you reproduced performance issue when checking this directly > with the shared storage mount, outside the VMs? > > On Tue, Sep 24, 2019 at 4:53 PM Vrgotic, Marko <M.Vrgotic@activevideo > .com> wrote: > Dear oVirt, > > I have executed some tests regarding IO disk speed on the VMs, > running on shared storage and local storage in oVirt. > > Results of the tests on local storage domains: > avlocal2: > [root@mpollocalcheck22 ~]# dd if=/dev/zero of=/tmp/test2.img bs=512 > count=100000 oflag=dsync > 100000+0 records in > 100000+0 records out > 51200000 bytes (51 MB) copied, 45.9756 s, 1.1 MB/s > > avlocal3: > [root@mpollocalcheck3 ~]# dd if=/dev/zero of=/tmp/test2.img bs=512 > count=100000 oflag=dsync > 100000+0 records in > 100000+0 records out > 51200000 bytes (51 MB) copied, 43.6179 s, 1.2 MB/s > > Results of the test on shared storage domain: > avshared: > [root@mpoludctest4udc-1 ~]# dd if=/dev/zero of=/tmp/test2.img bs=512 > count=100000 oflag=dsync > 100000+0 records in > 100000+0 records out > 51200000 bytes (51 MB) copied, 283.499 s, 181 kB/s > > Why is it so low? Is there anything I can do to tune, configure VDSM > or other service to speed this up? > Any advice is appreciated. > > Shared storage is based on Netapp with 20Gbps LACP path from > Hypervisor to Netapp volume, and set to MTU 9000. Used protocol is > NFS4.0. > oVirt is 4.3.4.3 SHE. > > > _______________________________________________ > Users mailing list -- users(a)ovirt.org > To unsubscribe send an email to users-leave(a)ovirt.org > Privacy Statement: < > _______________________________________________ > Users mailing list -- users(a)ovirt.org > To unsubscribe send an email to users-leave(a)ovirt.org > Privacy Statement: https://www.ovirt.org/site/privacy-policy/ > oVirt Code of Conduct: https://www.ovirt.org/community/about/communit > y-guidelines/ > List Archives: https://lists.ovirt.org/archives/list/users@ovirt.org/ > message/7XYSFEGAHCWXIY2JILDE24EVAC5ZVKWU/ -- Tony Albers - Systems Architect - IT Development Royal Danish Library, Victor Albecks Vej 1, 8000 Aarhus C, Denmark Tel: +45 2566 2383 - CVR/SE: 2898 8842 - EAN: 5798000792142