couchdb-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Randall Leeds <>
Subject Re: Which filesystem is best for deploying couchdb and why?
Date Thu, 16 Sep 2010 19:47:15 GMT
Disclaimer: I'm no file systems expert.

I recommend something with extents otherwise you might take a big
performance hit while couch deletes old db files after compaction.
Compression sounds cool as long as you can do it really fast (are
there setups where this happens in hardware?).

According to wikipedia it "still uses the big kernel lock (BKL) — a
global kernel-wide lock" which makes performance on multiple cores
It's big benefit, as I always understood it, is being able to pack
smile files together into single blocks. You will likely not have lots
of small files with Couch :-P

Delayed allocation might be a big performance win with a Couch. Since
outstanding writes are committed together in chunks and then fsync'd
all together I bet this feature would do good things for Couch

I'd recommend ext4 over ext3. Delayed allocation like xfs as well as
the multiblock allocator should make it much better than ext3. You
also get extents.

Some of the features of each sound interesting, but nothing that
stands out to me as "great for CouchDB". Snapshots and backups are
cool, but Couch is doing this for you already in a sense due to the
way the btree is appended: CouchDB documents are, in a sense,
copy-on-write. Checksumming is cool if you think it's important for
your data integrity. If you want snapshots for backup you can always
use CouchDB replication.

If you run any tests I'd be very, very interested in seeing your results.


On Thu, Sep 16, 2010 at 03:11, Metin Akat <> wrote:
> I'm sure almost everybody out there is using ext4/3 (including me),
> but what about filesystems like btrfs, zfs, reiserfs, xfs. Some of
> them have very appealing feature-sets (like compression for example,
> and we all know how greedy is couchdb for disk space).
> And I know that for example btrfs is not yet "recommended for
> production". But its time is coming. From what I see, Ubuntu 10.10
> works flawlessly on btrfs.
> So I'd be happy if we have some discussion on the topic, instead of
> "everybody uses ext4, just use it" kind of stuff :).
> Couchdb was "alpha software" for years, and we all used it in
> production, so we are not afraid of alpha/beta software, as long as
> it's good :)

View raw message