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Storage bottleneck when using RAID 1 ?
I have a UNIX server that hosts some fairly large Informix tables and
recently the servers performance has degraded quite dramatically. After investigating further it appears that this is down to a storage bottleneck, the server is around three years old and I just upgraded it's CPU's (dual P3 Tualatins). When installed RAID 1 was chosen as the RAID level but was that a mistake ?. I'd say that reads and writes to the server have increased by quite an amount (more reads than writes) so would say moving to RAID 5 give me a performance increase without having to upgrade any hardware ?. Thanks. Clive. |
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#3
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Clive,
RAID 5 is going to give you faster reads, but not necessarily faster writes. Have you considered RAID 0/1 (sometimes called RAID 10), it stripes across different sets of RAID 1 disks, giving you the benefits of both striping and mirroring. It uses a lot of disks and can work out expensive. I've had hardware vendors insist to me that modern RAID5 systems are much faster than they used to be, but I'd certainly investigate RAID 0/1 before you go for RAID 5. The other thing, is to try and pinpoint the bottleneck. Do you just have the DB's on this server or is there software, client processes, temporary sort files, etc on there. If so, you can segregate out the processes and put the guilty party on a separate disk set, perhaps striped across mirrored sets to increase speed. From personal experience, the biggest bottlenecks on DB's come from badly written software (whether it is running on the same server or from client machines). I've seen a simple product enquiry loop through 30 million records in order to find a single product (the server actually did this incredibly quickly, but the user just thought it was pants). It can be hard work tracing software problems (particularly if you have a 3rd paty software house that denies everything), but changing hardware to try and cater for bad programming/indexing is a bit like performance tuning a car's engine only to find the driver keeps the handbrake on. Good Luck! John wrote in message ... I have a UNIX server that hosts some fairly large Informix tables and recently the servers performance has degraded quite dramatically. After investigating further it appears that this is down to a storage bottleneck, the server is around three years old and I just upgraded it's CPU's (dual P3 Tualatins). When installed RAID 1 was chosen as the RAID level but was that a mistake ?. I'd say that reads and writes to the server have increased by quite an amount (more reads than writes) so would say moving to RAID 5 give me a performance increase without having to upgrade any hardware ?. Thanks. Clive. |
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John and Jochen,
Thanks for your replies, I've got the budget to replace the server and I'll think I'll do that as the current RAID controller doesn't support RAID 0+1/10 and I can use the current server for a project elsewhere (the servers around four years old as well). I allready liked the sound of RAID 0+1/10 and having two other people reccomend it as well is helpfull. Thanks. Clive. |
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#7
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'The old server will probably be taken home for "Research".' ... I wish
Seriously though if the if the server was a little younger (it's nearly four years old) and the RAID controller supported the level of RAID that I want then it would still be in service for years to come. Clive. "John Seed" wrote in message om... Hey, the lad works in IT. If he's got the budget, he's going to spend it. The old server will probably be taken home for "Research". John PS: Seriously though, don't assume a new server will solve all your problems. It's still worth trying to identify where the bottleneck is or it could just expand to fit whatever hardware you throw at it. |
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