[Xapian-discuss] Filesystems

Frank John Bruzzaniti frank.bruzzaniti at gmail.com
Wed Jul 1 11:00:32 BST 2009


Are you using any mount options optimisations like noatime or noboundary 
with xfs?
Are you using any mount option optimisations with ext4?

Arjen van der Meijden wrote:
> My colleague is testing several filesystems on our new search-machine. 
> He has been looking at a few of the filesystems available in the 2.6.30 
> linux kernel, ext2/3/4, xfs, btrfs, nilfs2 and reiser4.
> "Unfortunately" the new machine has 24GB ram and 4x ssd in raid5. To get 
> somewhat IO-bound results we had to cripple the machine (by making sure 
> it couldn't use 20gb of those 24gb for file-cache) *and* cherry-pick our 
> queries (only the heaviest with phrase-queries and such).
> In the normal scenario of having the full ram (or even 4gb) available 
> and the ssd's backing up any cache-miss, it is simply cpu-bound. And 
> that is with the fastest x86 2-socket cpu's available right now, a pair 
> of intel X5570's. The good news is that it actually appears to scale 
> very well when using more cpu-cores (this one has 8 cores with 8 
> hyper-threading cores) and that we can get about 90 searches per second 
> out of it, which is more than we do now per minute (and we haven't 
> benchmarked the compacted database yet).
> I.e. our results indicate that for our reads it hardly matters which 
> filesystem to pick, most of the database will be in RAM any way.
> With the crippled, extra-io, read-scenario, we do see differences in 
> performance between de filesystems tested.
> When finished, we'll have numbers for linear writes (copying the 25GB 
> database from another disk array), non-linear writes (updating the 
> database) and semi-linear writes (compacting the database) with 
> semi-linear (memory-backed) reads.
> And of course the numbers for the crippled read-scenario.
> So far ext4 and xfs seem to be the best choices, both in read and write 
> scenario's. But obviously, our numbers are done with ssd, not normal disks.
> We haven't yet tested the various mount/mkfs-options (apart from 
> enabling noatime), but we'll probably settle for ext4 and then try a few 
> options to better suit the filesystem to the underlying blockdevice. 
> After that we'll also try what the various compaction-options do to the 
> read-performance.
> Best regards,
> Arjen
> On 1-7-2009 3:18 James Aylett wrote:
>> On Tue, Jun 30, 2009 at 06:12:55PM -0700, Kevin Duraj wrote:
>>> Based on my observation Flint runs best on ext3 filesystems
>> I don't suppose you're able to share any of your numbers from this? I
>> know it's not always possible, but having something on the wiki would
>> be useful to people, if only to point them in useful directions of how
>> to construct their own testing. (I assume you were comparing against
>> JFS and XFS, maybe Reiser?)
>> J
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