Poor Performance WhenNumber of Files > 1M

Coly Li coyli at suse.de
Fri Aug 3 17:54:48 UTC 2007

How about the file size ? If the size is small, another performance kill should
be on disk inode layout. Because the order of access dentries of dir is probably
different from the order of allocating inodes in inode tables. This will make
much time wast on hard disk seeking for the first time.

Just FYI.


Sean McCauliff wrote:
> Hi all,
> I plan on having about 100M files totaling about 8.5TiBytes.   To see
> how ext3 would perform with large numbers of files I've written a test
> program which creates a configurable number of files into a configurable
> number of directories, reads from those files, lists them and then
> deletes them.  Even up to 1M files ext3 seems to perform well and scale
> linearly; the time to execute the program on 1M files is about double
> the time it takes it to execute on .5M files.  But past 1M files it
> seems to have n^2 scalability.  Test details appear below.
> Looking at the various options for ext3 nothing jumps out as the obvious
> one to use to improve performance.
> Any recommendations?
> Thanks!
> Sean
> ------
> Parameter one is number of files, parameter two is number of directories
> to write into.
> Dell MD3000 + LVM2. 2x7 10k rpm SAS disks 128k stripe RAID-0 for 3.8
> TiBytes of total storage.  Fedora Core 6 x86_64.  2xQuad Core Xeon.
> Default mount and ext3 options used.
> [root at galaxy filestore]# time /soc/abyss/test/fileSystemTest.pl 10000 1000
> real    0m1.054s
> user    0m0.128s
> sys     0m0.382s
> [root at galaxy filestore]# time /soc/abyss/test/fileSystemTest.pl 1000000
> 1000
> real    1m0.938s
> user    0m12.203s
> sys     0m40.358s
> [root at galaxy filestore]# time /soc/abyss/test/fileSystemTest.pl 10000000
> 1000
> real    13m39.881s
> user    2m6.645s
> sys     7m26.665s
> [root at galaxy filestore]# time /soc/abyss/test/fileSystemTest.pl 20000000
> 1000
> real    44m46.359s
> user    4m22.911s
> sys     17m2.792s

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