[svn.haxx.se] · SVN Dev · SVN Users · SVN Org · TSVN Dev · TSVN Users · Subclipse Dev · Subclipse Users · this month's index

Re: svn hotcopy vs. LVM snapshot

From: Phil Endecott <spam_from_subversion_users_at_chezphil.org>
Date: 2005-11-22 20:32:23 CET

Thanks for the reply.

I asked:
>> Has anyone investigated the relative merits of "svn hotcopy" and LVM
>> snapshots?

Phillip Susi wrote:
> The problem is that the snapshot is in an inconsistent state, as if the
> machine had crashed at that moment. You will need to fsck the snapshot
> to make sure the filesystem is ok before mounting it.

I believe that there is some "magic" in the LVM stuff to make this safe,
i.e. the filesystem is told to do some sort of flush before the snapshot
is taken, or something. The feature is designed specifically for things
like backups. (I'm hoping that someone who is reading this will know a
definitive answer...)

> In short, it is safer to svn hotcopy, because this guarantees that the
> saved information is consistent; i.e. does not contain half of a commit
> that was in progress.

In what sense is a "half commit" possible? It's atomic; by definition,
either a commit has happened, or it hasn't. If it's possible to
snapshot "during" a commit, surely subversion is broken. Or am I
missing something?



To unsubscribe, e-mail: users-unsubscribe@subversion.tigris.org
For additional commands, e-mail: users-help@subversion.tigris.org
Received on Tue Nov 22 20:38:58 2005

This is an archived mail posted to the Subversion Users mailing list.

This site is subject to the Apache Privacy Policy and the Apache Public Forum Archive Policy.