Re: [Xen-users] relocation time about 20sec? and yours?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> i have running xen-3.0.2 and my migration time for DomU from Server A to
> Server B is about 20sec. The Servers A and B are connected over 1GBit/s
> Links and the storrage is connected via iSCSI. The iSCSI volumes have a
> performance about 20-40MByte/s. Servers A is a 2x2GHz Xeon with 4GB Ram
> and Server B is a 1.8GHz AMD with 2GB Ram.
>
> The documentation states about some 60-300msec, so my qestion is:

That's the downtime to complete the migration.  In live migration, you still 
need to spend some time (20secs sounds reasonable) precopying memory over.  
The domain is only actually stopped for 60-300msecs but the whole process 
takes longer (nb. make sure you're passing the live migration flag - I think 
it's -l or --live)

> How long takes it on your Servers to migrate a DomU from A to B, what kind
> of storrage do you use.

We've used iSCSI, I think.  NBD should work fine, a SAN should also give good 
performance.

You should be able to use a local block device and sync it up with DRBD, in 
principle, but the last I heard was that the available DRBD release made that 
hard.  I know this was a problem that would be fixed by the multi-writer DRBD 
enhancements.

> And certainly how can i fasten this process?
>

You could balloon the domain down before migrating it to reduce the precopying 
time, but this will cost performance and so is probably not worth it.

> Any suggestion is appreciated.
HTH,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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