Disk IO testing, comparative study 2008


Two test nodes, named eastwood and newman, are configured for testing in summer 2008. 

Testing is performed under Scientific Linux 5.1 unless otherwise stated.

See also IO performance testing.


The basic hardware specs common to both nodes:

Manufacturer:  Penguin Computing

Model: Relion 230

Dual Intel(R) Xeon(TM) CPU 3.06GHz, w/ Hyper-threading

2 GB RAM, PC2100

6 IDE disks, 200GB each, all Western Digital "Caviar" series, model numbers starting with WD2000JB (there are some variations in the sub-model numbers, but I could find no documentation as to the distinctions amongst them).  Manufactured in late 2003 or early 2004.

The disks are on two controllers:

--onboard, Intel Corporation 82801CA Ultra ATA Storage Controller with 2 channels

  1. hda (primary master)
  2. hdc (secondary master)
  3. hdd (CD-ROM, secondary slave)

--PCI card, Promise Technology, Inc. PDC20268 (Ultra100 TX2)

  1. hde (primary master)
  2. hdf (primary slave)
  3. hdg (secondary master)
  4. hdh (secondary slave)


There are some RAID configurations that would not make much sense, such as combining a master and slave from the same channel into an array, beacuse of the inherent limitation of IDE/ATA that the master and slave on a single channel cannot be accessed simultaneously. 

Initial testing configuration is as follows:

On eastwood, no RAID is configured, and all drives are independent (other than the IDE master/slave connection).  The drives are configured as follows:

  • hda is part of a Logical Volume Group and hosts the OS on ext3
  • hdc -- ext2
  • hde -- ext2
  • hdf -- ext2
  • hdg -- ext3
  • hdh -- ext3

On newman two software RAID arrays are confrigured in addition to the system disk:

  • hda is part of a Logical Volume Group and hosts the OS on ext3
  • hdc, hde and hdg (all IDE masters) are part of a RAID5 (striped with distributed parity) array, with 256KB stripe size, ext3
  • hdf and hdh (both IDE slaves) are part of a RAID0 (striped, no parity) array, with 256KB stripe size, ext3