-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 11/25/07 01:28, Alex Turner wrote: > Why the hell would you buy a 1U chassis in the first place when > perfectly good cheap 4U chassis exists that will take 8 or more drives? > > 1U motherboards are a pain, 1U power supplies are a pain and 1U space > for drives sucks. > > Most tests I've seen these days show that there is very little actual > benefit from seperating pg_xlog and tablespace if you have a half decent > controller card. Infact you are better off putting it all on one nice > RAID 10 to get the good read performance that splitting it up will loose. > > if you don't have a decent controller card, RAID 0 will suck too. > Namely onboard SATA RAID often sucks. pg_xlog and tablespaces should be on as much different hardware as possible, to reduce the likelihood that a single part failure will knock out both directory structures. > Alex > > On Nov 24, 2007 12:06 PM, Steve Atkins < steve@xxxxxxxxxxx > <mailto:steve@xxxxxxxxxxx>> wrote: > > > On Nov 24, 2007, at 8:17 AM, Ron Johnson wrote: > > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA1 > > > > On 11/24/07 09:12, Scott Marlowe wrote: > >> On Nov 24, 2007 5:09 AM, Clodoaldo > >> < clodoaldo.pinto.neto@xxxxxxxxx > <mailto:clodoaldo.pinto.neto@xxxxxxxxx>> wrote: > >>> I will build a cheap server and I'm in doubt about what would the > >>> the > >>> best for performance: > >>> > >>> 1 - everything in one lonely fast 10,000 rpm Raptor HD; > >>> > >>> 2 - two cheap 7,200 rpm 16MB cache HDs like this: > >>> > >>> disk 1 - system and pg_xlog > > This doesn't really buy you much. The supposed advantage of having > pg_xlog on its own drive is so that the head doesn't need to seek. If > it's on the system drive it'll be competing with, at least, syslog. > > >>> disk 2 - pg_data without pg_xlog > >>> or a better arrange suggested by you; > >>> > >>> 3 - The two cheap HDs above in Raid 0. > >> > >> From a DBA perspective, none of those seem like a good choice, as > >> there's no redundancy. > >> > >> I'd make the two 7200 RPM drives a RAID-1 and have some redundancy so > >> a single disk failure wouldn't lose all my data. then I'd start > >> buying more drives and a good RAID controller if I needed more > >> performance. > > It depends on what the box is used for, but for most cases where the > data > is valuable, that sounds like a much better idea. > > For batch data crunching, where the data is loaded from elsewhere then > processed and reported on, the cost of losing the data is very low, and > the value of the machine is increased by RAID0-ing the drives to make > the crunching faster... RAID0 could be good. That's probably not the > case > here. > > > > > Remember: disks are *cheap*. Spend an extra US$250 and buy a couple > > of 500GB drives for RAID 1. You don't mention what OS you'll use, > > but if you really need cheap then XP & Linux do sw RAID, and FreeBSD > > probably does too. > > > > Disks aren't necessarily cheap. Disks are fairly expensive, especially > when you need more spindles than will fit into the servers chassis > and you > need to move to external storage. Disk n+1 is very expensive, likely > more expensive than the cheap 1U server you started with. > > Two, though, does seem to be false economy for a server that'll be > running a database, when you can get a 1U chassis that'll take 4 drives > pretty cheaply. - -- Ron Johnson, Jr. Jefferson LA USA %SYSTEM-F-FISH, my hovercraft is full of eels -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFHSSvAS9HxQb37XmcRAsWOAKCfO79c6HLqLDBNOYrzkaLaj1D47QCghVYF tIhKgVmBpV3XolRtkcd1+m0= =HqMl -----END PGP SIGNATURE----- ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
