Re: Looking for a cheap upgrade (RAID)
От | scott.marlowe |
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Тема | Re: Looking for a cheap upgrade (RAID) |
Дата | |
Msg-id | Pine.LNX.4.33.0305021512160.25254-100000@css120.ihs.com обсуждение исходный текст |
Ответ на | Re: Looking for a cheap upgrade (RAID) ("Chad Thompson" <chad@weblinkservices.com>) |
Ответы |
Re: Looking for a cheap upgrade (RAID)
(Josh Berkus <josh@agliodbs.com>)
Re: Looking for a cheap upgrade (RAID) (Shridhar Daithankar <shridhar_daithankar@persistent.co.in>) |
Список | pgsql-performance |
Seeing as you'll have 2 gigs of RAM, your swap partition is likely to grow cob webs, so where you put it probably isn't that critical. What I usually do is say take 4 120 Gig drives, allocate 1 gig on each for swap, so you have 4 gigs swap (your swap should be larger than available memory in Linux for performance reasons) and the rest of the drives split so that say, the first 5 or so gigs of each is used to house most of the OS, and the rest for another RAID array hosting the database. Since the root partition can't be on RAID5, you'd have to set up either a single drive or a mirror set to handle that. With that setup, you'd have 15 Gigs for the OS, 4 gigs for swap, and about 300 gigs for the database. The nice thing about RAID 5 is that random read performance for parallel load gets better as you add drives. Write performance gets a little better with more drives since it's likely that the drives you're writing to aren't the same ones being read. Since your swap os likely to never see much use, except for offline storage of long running processes that haven't been accessed recently, it's probably fine to put them on the same drive, but honestly, I've not found a great increase from drive configuration under IDE. With SCSI, rearranging can make a bigger difference, maybe it's the better buss design, i don't know for sure. Test them if you have the time now, you won't get to take apart a working machine after it's up to test it. :) On Fri, 2 May 2003, Chad Thompson wrote: > Can WAL and the swap partition be on the same drive? > > Thanks > Chad > ----- Original Message ----- > From: "Josh Berkus" <josh@agliodbs.com> > To: "Chad Thompson" <chad@weblinkservices.com>; "pgsql-performance" > <pgsql-performance@postgresql.org> > Sent: Friday, May 02, 2003 2:10 PM > Subject: Re: [PERFORM] Looking for a cheap upgrade (RAID) > > > Chad, > > > I realize that Im a raid on linux newbie so any suggestions are > appreciated. > > Im thinking I want to put this on an IDE Raid array, probably 0+1. IDE > seems > > to be cheap and effective these days. > > What ive been able to glean from other postings is that I should have 3 > > drives, 2 for the database w/ striping and another for the WAL. > > Well, RAID 0+1 is only relevant if you have more than 2 drives. Otherwise, > it's just RAID 1 (which is a good choice for PostgreSQL). > > More disks is almost always better. Putting WAL on a seperate (non-RAID) > disk > is usually a very good idea. > > > I would also appreciate raid hardware suggestions (brands, etc) > > And as always im not afraid to RTFM if someone can point me to the FM :-) > > Use Linux Software RAID. To get hardware RAID better than Linux Software > RAID, you have to spend $800 or more. > > > -- > -Josh Berkus > Aglio Database Solutions > San Francisco > > > ---------------------------(end of broadcast)--------------------------- > TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faqs/FAQ.html >
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