On Tue, 21 Oct 2003, Markus Wollny wrote: > Hi! > > > -----Ursprüngliche Nachricht----- > > Von: Shridhar Daithankar [mailto:[EMAIL PROTECTED] > > Gesendet: Dienstag, 21. Oktober 2003 08:08 > > An: [EMAIL PROTECTED] > > Betreff: Re: [GENERAL] Recomended FS > > > Can you compare ogbench results for the RAID and single IDE > > disks? It would be > > great if you could turn off write caching of individual > > drives in RAID and > > test it as well. > > One thing I can say from previous experiences is that the type of RAID > does matter quite a lot. RAID5, even with a quite expensive Adaptec > SCSI-hardware-controller, is not always the best solution for a > database, particularly if there's a lot of INSERTs and UPDATEs going on. > If you're not too dependant on raw storage size, your best bet is to use > the space-consuming RAID0+1 instead; the reasoning behind this is > probably that on RAID5 the controller has to calculate the parity-data > for every write-access, on RAID0+1 it just mirrors and distributes the > data, reducing overall load on the controller and making use of more > spindles and two-channel-SCSI.
Theory vs. real life. In Theory, RAID5 is faster because less data have to be written to disk. But it's true, many RAID5 controllers don't have enough CPU power. ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
