Re: [Moosefs-users] Backup strategies

[Atom P. <ap...@di...>]

On 04/03/2012 02:36 PM, Quenten Grasso wrote:
> I was planning to create hourly snapshots (as I understand the way
> they are implemented they don't affect performance unlike a vmware
> snapshot please correct me if I'm wrong) and copy these offsite to
> another mfs/cluster using rsync w/ snapshots on the other site with
> maybe a goal of 2 at most and using a goal of 3 on site.

Although snapshots don't increase the amount of storage used by the 
system, it effectively doubles the amount of metadata. For even 
medium-sized systems, making a snapshot of the complete system may 
actually decrease the security of the system by introducing problems 
with the amount of RAM and disk used by the metamaster.

On my system, with about 7 million files and 3GB of metadata, doing a 
daily snapshot for a week requires some 22GB+ of additional RAM in the 
metamaster and metalogger.

In other words, just because you /can/ do snapshots doesn't means you 
can do them without careful capacity planning. (And based on the number 
of people having issues with their metamaster I am very hesitant to 
recommend that strategy.)

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