Karl Pielorz wrote on 2017/09/20 16:54:



--On 20 September 2017 at 12:44:18 +0100 Roger Pau Monné
<roger....@citrix.com> wrote:

Is there some 'tuneable' we can set to make the 10.3 boxes more tolerant
of the I/O delays that occur during a storage fail over?

Do you know whether the VMs saw the disks disconnecting and then
connecting again?

I can't see any evidence the drives actually get 'disconnected' from the
VM's point of view. Plenty of I/O errors - but no "device destroyed"
type stuff.

I have seen that kind of error logged on our test kit - when
deliberately failed non-HA storage, but I don't see it this time.

Hm, I have the feeling that part of the problem is that in-flight
requests are basically lost when a disconnect/reconnect happens.

So if a disconnect doesn't happen (as it appears it isn't) - is there
any tunable to set the I/O timeout?

'sysctl -a | grep timeout' finds things like:

  kern.cam.ada.default_timeout=30


Yes, you can try to set kern.cam.ada.default_timeout to 60 or more, but it can has downside too.

Miroslav Lachman

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