Hi to all,
During verzion 3.x I was using freenas 9.x as iscsi-target shared
storage with 2 x GBit multipath(alua) connection.
Each host has 2 x Gbit Nic and evrything was working smooth and fast.
I could saturate both links up to 95% w/o any problems and traffic was
always correctly shared on both links.
Very often I must restore 16 VMs (800G archive) onto this freenas
"storage" (vulgaris PC with 5 disks / sata controller on board / zfs
raidz1 / ...)
and in this multipath/zfs scenario the result was perfect -> Both hosts
were restoring 8 VMs each in the same time to this storage , saturating
both storage links up to 90% .
But the most important information was that I/O% delay was allways lower
than CPU% .
But as soon as I switched to 4.x prox this story is not that nice any more.
Multipath works correctly but only on the OS level. So if we import
mpath lvm storage into prox 4.x everything gets too too slow.
When restoring only one VM at a time I/O% delay raises up to 40% and
there is no way to start another restore.
But , very interesting is that:
- if I format this iscsi target partition as linux and mount it on the
host, and than import it as "directory" in "storage" section, the
result is very very good again.
- if I mount this zfs storage as PV volume into both hosts , define two
LV and format them into linux and mount them into the hosts (now each
hosts is connected to the one LV on the same PV -> "dd" 65G from each
host onto its LV on the common PV shows 122MBs write speed each (more
than 240MBs on the multipath link)
But only when I import LVM as common PV into the prox hosts then things
get very very slow ....
It seems that OS is handling multipath correctly but as soon as prox
starts to manage it , things get very "underaverige"
So please an advice what could be so wrong in this my scenario that I
cannot get so good results from the 3.x platform ?
Thank you very much in advance and
BR
Tonci
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