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From Wout Mertens <wout.mert...@gmail.com>
Subject Re: Which filesystem is best for deploying couchdb and why?
Date Sat, 18 Sep 2010 09:23:50 GMT
Everything except the 4KB blocksize I would say. While ZFS and Btrfs are very different on-disk,
they are both Copy-On-Write filesystems with extents, compression and cheap snapshots. I don't
know how the 4KB blocksize settings translates onto Btrfs.

They are both really suited for the append-only workload CouchDB presents.

Wout.

On Sep 18, 2010, at 9:49 , Metin Akat wrote:

> What part of this blog post is relevant to btrfs?
> 
> On Fri, Sep 17, 2010 at 10:22 PM, Chris Anderson <jchris@apache.org> wrote:
>> On Thu, Sep 16, 2010 at 6:22 PM, Tyler Gillies <tyler@pdxbrain.com> wrote:
>>> Wow, thanks for the thought out writeup!
>>> 
>> 
>> here's a blog post http://letsgetdugg.com/2010/06/25/couchdb-on-zfs/
>> 
>>> On Thu, Sep 16, 2010 at 12:47 PM, Randall Leeds <randall.leeds@gmail.com>wrote:
>>> 
>>>> 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?).
>>>> 
>>>> reiserfs:
>>>> According to wikipedia it "still uses the big kernel lock (BKL) — a
>>>> global kernel-wide lock" which makes performance on multiple cores
>>>> suffer.
>>>> 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
>>>> 
>>>> xfs:
>>>> 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
>>>> performance.
>>>> 
>>>> ext(3|4)
>>>> 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.
>>>> 
>>>> btrfs/zfs:
>>>> 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.
>>>> 
>>>> -Randall
>>>> 
>>>> On Thu, Sep 16, 2010 at 03:11, Metin Akat <akat.metin@gmail.com> 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 :)
>>>> 
>>> 
>>> 
>>> 
>>> --
>>> http://www.readwriteweb.com/about#tyler
>>> 
>>> Ask me anything <http://tumble.pdxbrain.com/ask>!
>>> 
>> 
>> 
>> 
>> --
>> Chris Anderson
>> http://jchrisa.net
>> http://couch.io
>> 


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