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? > > > > > _______________________________________________ > Users mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/users > _______________________________________________ Users mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/users
