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

From: David Glasser <glasser_at_davidglasser.net>
Date: Tue, 8 Jan 2008 23:18:57 -0500

I'll commit it in a day or so. I assume your testing was with NFS and
local? (Checkouts and commits? Does it actually speed up checkups?)

--dave

On Jan 8, 2008 6:33 PM, Dan Christian <dchristian_at_google.com> wrote:
> 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 Čibej <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/
> >
>

-- 
David Glasser | glasser@davidglasser.net | http://www.davidglasser.net/
Received on 2008-01-09 05:19:07 CET

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