[DRBD-user] DRBD below or on top of LVM

[H.D.]

On 15.02.2007 10:56, Graham Wood wrote:
> The ability of XFS to freeze its filesystem certainly makes things 
> easier - but to script it using that you'll need to be very careful.  
> Effectively what you're going to want to do is:

I've read in some other post that lvcreate -s might block when XFS is 
frozen and that in general freezing is not needed. Is that true? I think 
the database will call fsync a few hundred times a second, at least 
after each COMMIT and after each write to the WAL.

PostgreSQL should recover fine with lost data in case of a crash -- 
given that fsync has done what it was supposed to do -- guarantee that 
WAL records have physically mad it to the disc spindles (or at least a 
BBU backed write cache).

Does DRBD or LVM alter fsync behavior? To my understanding they should 
not. If they do not, why do I need to freeze the FS?

Thanks!

-- 
Regards,
H.D.