Re: [PERFORM] seqential vs random io
I would tell him to go for the random, which is what most DBs would be by nature. What you need to understand will be the cache parameters, read/write cache amount, and stripe size, depending on your controller type and whatever it defaults to on these things. Thanks, Anjan -Original Message- From: David Parker [mailto:[EMAIL PROTECTED] Sent: Mon 5/23/2005 4:58 PM To: pgsql-performance@postgresql.org Cc: Subject: [PERFORM] seqential vs random io I just got a question from one our QA guys who is configuring a RAID 10 disk that is destined to hold a postgresql database. The disk configuration procedure is asking him if he wants to optimize for sequential or random access. My first thought is that random is what we would want, but then I started wondering if it's not that simple, and my knowledge of stuff at the hardware level is, well, limited. If it were your QA guy, what would you tell him? - DAP -- David ParkerTazz Networks(401) 709-5130 ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [PERFORM] seqential vs random io
David, > > I just got a question from one our QA guys who is configuring a RAID 10 > > disk that is destined to hold a postgresql database. The disk > > configuration procedure is asking him if he wants to optimize for > > sequential or random access. My first thought is that random is what we > > would want, but then I started wondering if it's not that simple, and my > > knowledge of stuff at the hardware level is, well, limited. > > > > If it were your QA guy, what would you tell him? Depends on the type of database. OLTP or Web == random access. Data Warehouse == sequential access. -- --Josh Josh Berkus Aglio Database Solutions San Francisco ---(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
Re: [PERFORM] seqential vs random io
David Parker wrote: > I just got a question from one our QA guys who is configuring a RAID 10 > disk that is destined to hold a postgresql database. The disk > configuration procedure is asking him if he wants to optimize for > sequential or random access. My first thought is that random is what we > would want, but then I started wondering if it's not that simple, and my > knowledge of stuff at the hardware level is, well, limited. > > If it were your QA guy, what would you tell him? > > - DAP Random. Sequential is always pretty fast, it is random that hurts. The only time I would say sequential is if you were planning on streaming large files (like iso images) with low load. But for a DB, even a sequential scan will probably not be that much data. At least, that's my 2c. John =:-> signature.asc Description: OpenPGP digital signature
[PERFORM] seqential vs random io
I just got a question from one our QA guys who is configuring a RAID 10 disk that is destined to hold a postgresql database. The disk configuration procedure is asking him if he wants to optimize for sequential or random access. My first thought is that random is what we would want, but then I started wondering if it's not that simple, and my knowledge of stuff at the hardware level is, well, limited. If it were your QA guy, what would you tell him? - DAP--David Parker Tazz Networks (401) 709-5130
