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[Xen-devel] Xrenstore and many save/restore cycles...

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Xrenstore and many save/restore cycles...
From: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
Date: Wed, 9 May 2007 18:09:14 +0200
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Thread-topic: Xrenstore and many save/restore cycles...
Let me first say that I have very little understanding of xenstore, as
it's not an area of Xen that I normally work in. If I've completely
missed something, please let me know.

I've been running a script over the (extended) weekend which saves and
restores HVM domains. In this case, two different domains. 

At this moment in time (around 6000 save/restore operations total),
xenstored is using about 900MB of memory (which is a bit excessive on my
256MB Dom0). Thrashing of the swap is consuming enough time that my
machine is unable to cope with running the domains satisfactorily at
this time. 

Using xenstored-list, I see hundreds (so far) of instance information of
"old" domains that have been killed when being saved, and created with a
new ID when restored. So I've got (I'm guessing) some 6000 or so domains
stored in xenstore. 

Is this something intended, and if so, would [I'm asking because I
haven't tried it] the same effect be expected if 6000 domains where
created and destroyed? If so, what is the purpose of keeping information
about a domain that is no longer there?

I can certainly see problems with servers that for one reason or another
save/restore several domains daily - after a few months, there will be
LOTS of data in the xenstore and potential swap-thrashin causing
problems, or what???


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