Strip size of a stripped disk set.

Posted in 1998

Albert wisse — Mon, 23 Feb 1998 10:26:38 +0100 — source: Informix-list mailing list archive (1991-1998)

<HTML> What is the recommended strip size for stripped disk set, 64K/32K/16K or 8K. Expl. I have placed all the chunks in use on the filesystem and the file system is on a disk subsystem with 5 disks in stripping mode. The disks are mirrored are mirrored for safety. The strip set used is now the default one and that is 64K. The problem that I have is that I don't see the performance that I expect. My settings: LRUS                           61 CLEANERS                76 LRUS_MAX_DIRTY   5 LRUS_MIN_DIRTY    3 BUFFERS                    65536 PDQPRIORITY            75 NUMVPS                        3 The hardware is: Sun Enterprise server with four 250Mhz CPU's, 1280MB physical memory, SPARC Enterprise Network Array (SENA) A5000 disk subsystem with two times seven 9GB disk and is dual channel, each 100MB fibre. The Informix chunks are placed on the file system, the file system is on a stripped disk set with five disks and with a strip size of 64K, RAID level 0+1 What I see: During meanly inserts is see a high amount of buffwaits, almost no FG, more LRUS writes then Chunk writes around four times more LRUS writes then Chunk writes.Checkpoint time 10 till 20 seconds, which is to high When I look at the disk load on the disk subsystem then I see a moderate load of the disks around 20% so I wonder why Informix behaves this way, is this due the fact I the filesystem or do I  have to increase the number of LRUS and CLEANERS further ?. Do I have to decrease the trip size ?. Regards, Albet Wisse              </HTML>