[Cialug] VMs & Replication

[Matthew Nuzum]

On Fri, Mar 18, 2011 at 2:28 PM, Matthew Steven <matthew at geniusweb.com>wrote:

> On 03/18/2011 12:48 PM, Matthew Nuzum wrote:
>
>>
>> Matt, you take the snapshots outside of the VM? Doesn't that cause
>> potential for consistency problems?
>>
>>  Absolutely.
>
> Even though LVM sync's everything to disk on the original volume before the
> snapshot COW starts, that doesn't necessarily guarantee consistency since
> the database will do with the data as it wilt.
>
> Coordinating a flush tables/lock before the snapshot creation is a good way
> to handle that. Or if that's likely to be mis-timed or inconvenient in your
> deployment, you can also just ensure that the system dumps the tables to
> disk regularly. Or use the db's built in syncronization. The list goes on
> and on!
>
>
You say that so candidly. Let me just confirm that what I understand from
your statement is that using this technique requires caution and probably
bears the same hassles as rebooting a machine that had the power cord
pulled, right?

-- 
Matthew Nuzum
newz2000 on freenode, skype, linkedin, identi.ca and twitter

"An investment in knowledge pays the best interest." -Benjamin Franklin
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