[REVIEW] Subsection "Choosing a Data Store"

Ben Collins-Sussman sussman at red-bean.com
Thu Jun 12 08:54:25 CDT 2008

It's a long known issue with FSFS:   each change uploaded goes into a
txn/ directory as the commit progresses.  But when the commit is
finalized, the FSFS code has to assemble lots of of small files in the
txn/ directory into a single new revision file.  If the commit
modified 20,000 files, then it may take a very long time to create the
revision file.

In practice, it's not really an issue.  In theory, it's an edge-case
of FSFS which doesn't scale well.

On Thu, Jun 12, 2008 at 8:48 AM, Karl Heinz Marbaise <khmarbaise at gmx.de> wrote:
> Hi,
> i would like to ask a little bit about the subsection "FSFS" and the
> Table 5.1 Repository data store comparison:
> Table 5.1.1:
> "Faster overall, but finalization delay may cause client timeouts"
> and
> Subsection "FSFS":
> "FSFS also has a longer delay when finalizing a commit, which could"
> "in extreme cases cause clients to time out while waiting for a response".
> Does this mean there is bug containing in SVN for FSFS or is this just
> to give a hint about an "known issue" or does this have other
> reasons...may be this can produce unstableness if read by users...
> AFAIK in SVN 1.5 there exist an opportunity to improve the commit speed
> if you put the transaction area to an local hard drive whereas the db
> area is living on a different kind of storage (e.g. SAN)...described in
> the blog...
> May be someone can enlighten me a little bit about the above....
> Thanks in advance...
> Kind regards
> Karl Heinz Marbaise
> --
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