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Re: proposed: move FSFS protorevs out of the transactions dir

From: Dan Christian <dchristian_at_google.com>
Date: Tue, 8 Jan 2008 15:33:11 -0800

This works for me under simple testing (just checkouts and commits).
It cuts the total time spent in file system operations roughly in half
(compared to everything on NFS). That should be a big win for
scalability!

Can this go in?
-Dan C

On Dec 25, 2007 7:14 PM, David Glasser <glasser_at_davidglasser.net> wrote:
> On Dec 25, 2007 6:01 PM, Branko ╚ibej <brane_at_xbc.nu> wrote:
> > David Glasser wrote:
> > > In already-bumped FSFS version 3, store the protorev and its lock
> > > separately from the rest of the transaction metadata, to make it easy
> > > for administrators to put the non-protorev metadata on a different
> > > filesystem from the immutable filesystem.
> > >
> >
> > Wouldn't doing that change an atomic rename to a non-atomic cross-device
> > move?
>
> Actually, avoiding that is the point :-)
>
> It's already the case that the move-into-place code in FSFS checks for
> a cross-device error, and does a copy instead in that case. Note,
> though, that the "copy" is actually "copy to temporary file, then
> atomically rename".
>
> However, the point here is I want to make it possible to store the txn
> metadata that *doesn't* get atomically moved on a different device,
> and leave the proto-rev on the same device as the revs. The use case
> I'm imagining would be to make db/transactions/ a symlink to local
> disk, but leave db/txn-protorevs/ on the same device as db/revs/.
>
> --dave
>
>
> --
> David Glasser | glasser@davidglasser.net | http://www.davidglasser.net/
>
Received on 2008-01-09 00:33:25 CET

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