Strange delete performance using XFS

Thomas Kaehn
2007-04-04T13:24:27Z

Hi,

I've got a strange problem on one machine using XFS. Deleting large
directories (containing about 100000 files, 20k each) using "rm -rf"
lasts nearly as long as creating the the files using a bash loop.

The machine is running Debian Sarge with a vanilla 2.6.20.3 kernel.
CPU: Dual Xeon(TM) CPU 3.20GHz
RAM: 4 GB
RAID10: 4x 320 GB disks connected to 3ware 9550SXU-8LP
(Firmware Version = FE9X 3.08.00.004)

The XFS was first created using default options and later on with
"-d su=64k,sw=2 -l su=64k" which improved overall performance
but not delete performance.

Has anyone realized similar effects? On a different server (Dell 6850)
the directory can be deleted within seconds. What could be the reason
for the huge difference in delete performance?

Please see below for "time" output.

| # time for i in `seq 1 100000`; do dd if=/dev/zero of=$i bs=1k count=20 >/dev/null 2>&1; done
|
| real 6m6.814s
| user 0m30.290s
| sys 2m42.562s
| # time rm -rf y
|
| real 5m18.034s
| user 0m0.036s
| sys 0m8.169s

In contrast to this the result on the Dell machine looks more
reasonable:

| # time for i in `seq 1 100000`; do dd if=/dev/zero of=$i bs=1k count=20 >/dev/null 2>&1; done
|
| real 9m26.658s
| user 0m24.134s
| sys 3m3.623s
| # time rm -rf x
|
| real 0m10.254s
| user 0m0.124s
| sys 0m10.105s

Ciao,
Thomas

PS: Using JFS and ext3 it is also possible to delete the above directory
in a couple of seconds. Only XFS seems problematic in this regard on
this system.
--
Thomas Kähn WESTEND GmbH | Internet-Business-Provider
Technik CISCO Systems Partner - Authorized Reseller
Im Süsterfeld 6 Tel 0241/701333-18
tk@westend.com D-52072 Aachen Fax 0241/911879
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Die Gesellschaft ist eingetragen im Handelsregister Aachen unter HRB 7608
Geschäftsführer: Thomas Neugebauer, Thomas Heller, Michael Kolb