Tutorial on how to backup/restore cyrus

[Simon Matter]

>> I don't completely agree here, there are ways to do snapshots without
>> any
>> downtime for example in a SAN environment or using filesystem or LVM
>> based
>> snapshot methods. However, it does not mean your snapshots are really
>> consistent from the aplications point of view.
>
> And that's the big question: How inconsistent can things be without
> shutting down
> cyrus?

I think nobody can really tell you. There are several possible
inconsistencies which depend on how you are doing snapshots or backups and
what filesystem you are using. However, exactly the same inconsistencies
will show up when your box crashes (kernel panic, power failure) and
properly configured systems should survive this without loosing much. Of
course, one has to make sure that the obvious is properly configured like
for example disabling raid/disk write caches with no battery backup or
making sure that the OS/filesystem really writes data out to the disk when
the application thinks it has been written. It's not always an easy task
and you will usually loose some performance by disabling those dangerous
tuning things.

Simon