[Bug 212681] I/O is slow for FreeBSD DOMu on XenServer

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=212681

--- Comment #8 from karl at pielorz.com ---
(In reply to rainer from comment #7)

Our config here is very similar - HP Proliant DL380 Gen -9- though, with local
SAS disks - which we use for 'Local Storage' for XenServer, and then iSCSI off
to a Synology NAS we use for primary storage of our VM's.

>On local storage, the realworld-test is even slower.

This troubles me, as we don't see that - but we are running the test on
un-contended local storage (you don't say if you are).

The times you show for that last dd run - seem to vary quite a lot:

1342177280 bytes transferred in 22.239869 secs (60350053 bytes/sec)
1342177280 bytes transferred in 38.072567 secs (35253133 bytes/sec)
1342177280 bytes transferred in 5.782933 secs (232092820 bytes/sec)
1342177280 bytes transferred in 7.891797 secs (170072452 bytes/sec)
1342177280 bytes transferred in 12.598706 secs (106532947 bytes/sec)
1342177280 bytes transferred in 7.917661 secs (169516892 bytes/sec)
13421772800 bytes transferred in 147.423047 secs (91042568 bytes/sec)

Especially that last one. How busy is the node? / local disks?

At this stage I'd be tempted to re-run the tests while on FreeBSD looking at
the output of something like:

  iostat -x 1

(which will show what FreeBSD thinks the disk service time, % busy etc. are) -
and on Dom0 providing the local storage running:

  iostat -x 1 | egrep -e "(^Device)|(^sd*)"

Which will do the equivalent for Xen.

Things to look out for are high % busy, and service time / queue depths.

At this point I'm not sure filling the ticket with reams of debug / command
output is helping much - it might be better to close this ticket - and revert
to email to see if we can narrow things down to a possible cause, before
re-opening the ticket again with more specific information.

-Karl

-- 
You are receiving this mail because:
You are the assignee for the bug.