[linux-audio-dev] RAID and Low Latency

New Message Reply About this list Date view Thread view Subject view Author view Other groups

Subject: [linux-audio-dev] RAID and Low Latency
From: Fred Gleason (fredg_AT_wava.com)
Date: Tue Nov 13 2001 - 01:34:17 EET

I've been dealing with an interesting situation here regarding a system
that is running three software RAID arrays. The layout consists of two
RAID1 arrays sharing two IDE drives and a RAID5 array running on five SCSI
drives (four active and one on hot standby). Latency tests on the system
show a very regular series of latency spikes occurring at around 5.2
second intervals during the disk write phase. They do not appear to be
particularly related to the underlying physical bus -- they appear in
tests of both the IDE and SCSI based arrays. Even more interestingly,
disk tuning and/or application of the ll patch seem to make very little
difference in the test results.

I've posted the test results at http://www.wava.com/ll_results. Has
anyone out there done any work regarding RAID as it bears upon low
latency?

Cheers!

|-------------------------------------------------------------------------|
|Frederick F. Gleason, Jr.|WAVA Radio - 105 FM |Voice: 1-(703)-807-2266 |
| Director of Engineering |1901 N. Moore Street| FAX: 1-(703)-807-2245 |
| |Arlington, VA 22209 | Web: http://www.wava.com|
|-------------------------------------------------------------------------|
| Documentation is like castor oil: managers know it must be good |
| because programmers hate writing it so much. |
| -- Anonymous |
|-------------------------------------------------------------------------|

New Message Reply About this list Date view Thread view Subject view Author view Other groups

This archive was generated by hypermail 2b28 : Tue Nov 13 2001 - 01:30:38 EET