[ovirt-users] Poor iSCSI Performance
InterNetX - Juergen Gotteswinter
jg at internetx.com
Thu Feb 19 09:35:48 UTC 2015
Hi,
already captured some iscsi Traffic of both Situations and compared them?
MTU maybe?
Juergen
Am 18.02.2015 um 02:08 schrieb John Florian:
> Hi all,
>
> I've been trying to resolve a storage performance issue but have had no
> luck in identifying the exact cause. I have my storage domain on iSCSI
> and I can get the expected performance (limited by the Gbit Ethernet)
> when running bonnie++ on:
>
> * a regular physical machine configured with the iSCSI initiator
> connected to a dedicated iSCSI test target -- thus oVirt and VM
> technology are completely out of the picture
> * my oVirt host with the initiator connected to that same dedicated
> target -- thus I have an iSCSI connection on the oVirt host but I'm
> not using the iSCSI connection provided by oVirt's storage domain
> * a VM (hosted by oVirt) with the initiator (inside the VM) connected
> to that target -- thus bypassing oVirt's storage domain and the
> virtual disk it provides this VM
>
> However, if I just use a regular virtual disk via oVirt's storage domain
> the performance is much worse. I've tried both VirtIO and VirtIO-SCSI
> and have found no appreciable difference.
>
> Here's a typical example of the poor performance I get (as tested with
> bonnie++) with the normal virtual disk setup:
>
> # bonnie++ -d . -r 2048 -u root:root
> <snip>
> Version 1.96 ------Sequential Output------ --Sequential Input-
> --Random-
> Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
> --Seeks--
> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
> /sec %CP
> narvi-f21.double 4G 806 91 18507 1 15675 1 3174 56 33175 1
> 176.4 3
> Latency 15533us 8142ms 2440ms 262ms 1289ms
> 780ms
> Version 1.96 ------Sequential Create------ --------Random
> Create--------
> narvi-f21.doubledog -Create-- --Read--- -Delete-- -Create-- --Read---
> -Delete--
> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
> /sec %CP
> 16 13641 24 +++++ +++ 22702 17 18919 31 +++++ +++
> +++++ +++
> Latency 27724us 247us 292us 71us 30us
> 172us
>
> For comparison, here's what I see if I run the same test, same VM, same
> host but this time the file system is mounted from a device obtained
> using iscsi-initiator-utils within the VM, i.e., the 3rd bullet config
> above:
>
> bonnie++ -d . -r 2048 -u root:root
> <snip>
> Version 1.96 ------Sequential Output------ --Sequential Input-
> --Random-
> Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
> --Seeks--
> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
> /sec %CP
> narvi-f21.double 4G 2051 89 103877 4 36286 3 4803 88 88166 4
> 163.6 3
> Latency 7724us 191ms 396ms 48734us 73004us
> 1645ms
> Version 1.96 ------Sequential Create------ --------Random
> Create--------
> narvi-f21.doubledog -Create-- --Read--- -Delete-- -Create-- --Read---
> -Delete--
> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
> /sec %CP
> 16 6531 18 +++++ +++ 16388 20 5924 15 +++++ +++
> 17906 23
> Latency 15623us 64us 92us 1281us 14us
> 256us
>
> My host is Fedora 20 running oVirt 3.5 (hosted-engine). VM is running
> Fedora Server 21. Tonight I tried updating the host with the Fedora
> virt preview repo and I didn't see any significant change in the
> performance. Where should I look next?
>
>
>
>
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