[sheepdog-users] plan for Sheepdog 1.0 and new organization
wenhao at zelin.io
Thu May 23 14:51:33 CEST 2013
On Thu, May 23, 2013 at 7:10 PM, Liu Yuan <namei.unix at gmail.com> wrote:
> On 05/23/2013 07:03 PM, MORITA Kazutaka wrote:
>> I think of improving the current recovery codes in near future so that
>> the recovery thread doesn't affect VM I/O as far as it can.
> It looks to me very hard, at least very hard to implement transparently.
> Many targets contradict themselves, to name a few:
> 1 'force recovery' after cluster crash will want the full speed
> 2 VM don't want recovery take its IO channel but want it to be get done
> as soon as possible
> 3 People want to check run as fast as possible but don't want it to
> interfere with VM.
Yes, there are definitely tradeoff here. We could still make it better, though.
1. If admins trigger 'force recovery' with a special 'urgent' flag,
the recovery I/O should be done as fast as possible. In normal case,
the priority can be lower.
2. Because permanent failure is far less frequent than the temporary
failure, recovering asap seems not that urgent in most cases unless
admin trigger an "urgent" recovery like 1.
3. VDI check should not interfere the running VMs anyway, I think.
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