All, I have a 13 disk (250G each) software raid 5 set using 1 16 port adaptec SATA controller. I am very happy with the performance. The reason I went with the 13 disk raid 5 set was for the space NOT performance. I have a single postgresql database that is over 2 TB with about 500 GB free on the disk. This raid set performs about the same as my ICP SCSI raid controller (also with raid 5). That said, now that postgresql 8 has tablespaces, I would NOT create 1 single raid 5 set, but 3 smaller sets. I also DO NOT have my wal and log's on this raid set, but on a smaller 2 disk mirror. Jim ---------- Original Message ----------- From: Greg Stark <gsstark@xxxxxxx> To: Alex Turner <armtuk@xxxxxxxxx> Cc: Greg Stark <gsstark@xxxxxxx>, Arshavir Grigorian <ag@xxxxxxxxx>, linux-raid@xxxxxxxxxxxxxxx, pgsql-performance@xxxxxxxxxxxxxx Sent: 14 Mar 2005 15:17:11 -0500 Subject: Re: [PERFORM] Postgres on RAID5 > Alex Turner <armtuk@xxxxxxxxx> writes: > > > a 14 drive stripe will max out the PCI bus long before anything else, > > Hopefully anyone with a 14 drive stripe is using some combination of 64 bit > PCI-X cards running at 66Mhz... > > > the only reason for a stripe this size is to get a total accessible > > size up. > > Well, many drives also cuts average latency. So even if you have no need for > more bandwidth you still benefit from a lower average response time by adding > more drives. > > -- > greg > > ---------------------------(end of broadcast)--------------------------- > TIP 9: the planner will ignore your desire to choose an index scan if your > joining column's datatypes do not match ------- End of Original Message ------- - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
