Well, more like they both are allowed to issue disk requests and the magical "clustered file system" manages locking, etc.
In reality, any disk is only reading/writing to one part of the disk at any given time, of course, but that in the multiple initiator deal, multiple streams of requests from multiple hosts can be queued. -----Original Message----- From: Bruce Momjian [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 19, 2005 12:16 PM To: Mohan, Ross Cc: pgsql-performance@postgresql.org Subject: Re: [PERFORM] How to improve db performance with $7K? Mohan, Ross wrote: > Clustered file systems is the first/best example that > comes to mind. Host A and Host B can both request from diskfarm, eg. So one host writes to part of the disk and another host writes to a different part? --------------------------------------------------------------------------- > -----Original Message----- > From: Bruce Momjian [mailto:[EMAIL PROTECTED] > Sent: Tuesday, April 19, 2005 12:10 PM > To: Mohan, Ross > Cc: pgsql-performance@postgresql.org > Subject: Re: [PERFORM] How to improve db performance with $7K? > > > Mohan, Ross wrote: > > The only part I am pretty sure about is that real-world experience > > shows SCSI is better for a mixed I/O environment. Not sure why, > > exactly, but the command queueing obviously helps, and I am not sure > > what else does. > > > > || TCQ is the secret sauce, no doubt. I think NCQ (the SATA version > > || of per se drive request reordering) > > should go a looong way (but not all the way) toward making SATA > > 'enterprise acceptable'. Multiple > > initiators (e.g. more than one host being able to talk to a drive) is a > > biggie, too. AFAIK only SCSI > > drives/controllers do that for now. > > What is 'multiple initiators' used for in the real world? > > -- > Bruce Momjian | http://candle.pha.pa.us > pgman@candle.pha.pa.us | (610) 359-1001 > + If your life is a hard drive, | 13 Roberts Road > + Christ can be your backup. | Newtown Square, Pennsylvania 19073 > > ---------------------------(end of > broadcast)--------------------------- > TIP 6: Have you searched our list archives? > > http://archives.postgresql.org > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
