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Re: FSFS vs BDB

From: Jan Hendrik <list.jan.hendrik_at_gmail.com>
Date: Thu, 13 Nov 2008 22:19:43 +0100

Concerning Re: FSFS vs BDB
Mark Eichin wrote on 13 Nov 2008, 14:55, at least in part:

> On Thu, Nov 13, 2008 at 5:23 AM, Jan Hendrik
> <list.jan.hendrik_at_gmail.com> wrote:
>
> > Two things keep us from switching to FSFS even just for a
> > practical test period:
> >
> > -- Never touch a running system. And BDB runs now.
>
> Definitely. (And you've probably been doing regular "svnadmin dump"
> backups, so even if there were still corruption issues, you'd be able
> to recover from them...)

Part of the post-commit hook is an incremental dump added. At
some "round" points pristine incremental dumps (e.g. revs. 1-500)
are stored away and a new one started for the hook.

> > -- I don't like the idea of having thousands of folders with
> > thousands of files each. It raises the chance of troubles and I
> > guess one damaged file would make the repository as inaccessible as
> > a corrupted DB file.
>
> That, I'd have to take issue with - pre 1.5 you have *two* directories
> with thousands of files each (you have a pair of files per *delta*, it
> doesn't matter what your hierarchy looks like); in 1.5 with sharding,
> you probably have hundreds but with only a thousand files each - and
> they're *static*, none of these files are written to once created.
> This is far less filesystem churn than, say, my personal photo gallery
> produces :-) On top of that, the unix filesystem has had a lot more
> scrutiny in a much wider range of cases than BDB itself ever will.

I should have added NTFS filesystem.

> > Just my tuppence, I'm no expert in neither SVN nor BDB internals.
>
> I've looked at them more closely than I'd hoped to (my name is on some
> of the very early BDB bugfixes from the Kerberos days, which is one
> reason I'm a little twitchy about it :-)

There you could do more than I :-)

Jan Hendrik
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Received on 2008-11-13 22:16:45 CET

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