[ovirt-users] Re: very very bad iscsi performance
FYI, I just tried it with direct lun.
it is as bad or worse.
I dont know about that sg io vs qemu initiator, but here is the results.
15223: 62.824: IO Summary: 83751 ops, 1387.166 ops/s, (699/681 r/w), 2.7mb/s, 619us
cpu/op, 281.4ms latency
15761: 62.268: IO Summary: 77610 ops, 1287.908 ops/s, (649/632 r/w), 2.5mb/s, 686us
cpu/op, 283.0ms latency
16397: 61.812: IO Summary: 94065 ops, 1563.781 ops/s, (806/750 r/w), 3.0mb/s, 894us
cpu/op, 217.3ms latency
----- Original Message -----
From: "Paolo Bonzini" <pbonzini(a)redhat.com>
To: "Nir Soffer" <nsoffer(a)redhat.com>
Cc: "Philip Brown" <pbrown(a)medata.com>, "users"
<users(a)ovirt.org>, "qemu-block" <qemu-block(a)nongnu.org>,
"Stefan Hajnoczi" <stefanha(a)redhat.com>, "Sergio Lopez Pascual"
<slp(a)redhat.com>, "Mordechai Lehrer" <mlehrer(a)redhat.com>
Sent: Monday, July 20, 2020 3:46:39 PM
Subject: Re: [ovirt-users] very very bad iscsi performance
Il lun 20 lug 2020, 23:42 Nir Soffer <nsoffer(a)redhat.com> ha scritto:
I think you will get the best performance using direct LUN.
Is direct LUN using the QEMU iSCSI initiator, or SG_IO, and if so is it
using /dev/sg or has that been fixed? SG_IO is definitely not going to be
the fastest, especially with /dev/sg.
Storage
domain is best if you want
to use features provided by storage domain. If your important feature
is performance, you want
to connect the storage in the most direct way to your VM.
Agreed but you want a virtio-blk device, not SG_IO; direct LUN with SG_IO
is only recommended if you want to do clustering and other stuff that
requires SCSI-level access.
Paolo