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

From: Dan Christian <dchristian_at_google.com>
Date: Wed, 9 Jan 2008 11:19:42 -0800

It's just my usual micro benchmark. I total over a series of
checkouts and commits. I doubt it affects checkouts. I could show
results at each step if that helps (it's a ton of data to sift
through).

The repo was on NFS, but the transactions directory was symlinked to a
directory on local disk.

-Dan C

On Jan 8, 2008 8:18 PM, David Glasser <glasser_at_davidglasser.net> wrote:
> 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 20:19:58 CET

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