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mike123
Master Smack Fu Yak Hacker
1462 Posts |
 Posted - 2004-08-11 : 19:23:58
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| Currently I have a dual 2.8 XEON / 2gb / raid 1 array (2 drives) as my database server.What type of performance boost would upgrading to raid 0+1 give me ? (4 drives), and how would this compare with a raid 5 (3 drives)I know this is a pretty general question, but any input is appreciated.Thanks again,mike123 |
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eyechart
Master Smack Fu Yak Hacker
3575 Posts |
Posted - 2004-08-11 : 20:12:41
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| RAID 5 has a pretty significant write penalty. Many systems mitigate this with a battery backed write cache though.Do you have your system files, swap file and database files all on the same RAID 1? You might be better off just creating a separate RAID 1 that housed your database files, and move them off of the existing RAID 1.I like having the system on a separate 2 disk RAID 1 because of convenience of pulling a drive to create a quick backup (system is shutdown of course). We usually do this before major OS upgrades(just in case).Anyway, adding a second RAID 1 will be easy for you, plus you'll have the ability to perform that quick OS backup if you so choose. On a small system like yours RAID 5 doesn't give you as much flexibility and there is a potential for worse performance if you do not have a good RAID controller w/write cache. -ec |
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MichaelP
Jedi Yak
2489 Posts |
Posted - 2004-08-11 : 20:26:52
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| If it were me, I'd keep the existing RAID 1 array and leave your TXLogs and TempDB on that. Get a 4 or 6 disk RAID 0/1 array and only put your Data files on it (MDF's).I've got a production system that has everything on one big RAID 5 array and the write penality is putting a hurting on us right now. I'd avoid RAID 5 if you can afford to. If not, do what I said above, except put your data on the RAID 5 array and leave the TXLogs on the RAID 1.I should have asked this question before I replied but here goes:Is your database read heavy or write heavy or balanced between the two?Read Heavy RAID 5 might not be bad for youWrite Heavy RAID 0/1 is the way to goBalanced I'd prob go RAID 0/1 if you can afford to.Michael<Yoda>Use the Search page you must. Find the answer you will.</Yoda> |
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mike123
Master Smack Fu Yak Hacker
1462 Posts |
Posted - 2004-08-12 : 22:11:12
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| I'd say my application is more on the READ heavy side, altho I do not have any numbers to back that up. I'd say its pretty high definately over 60/40 but with caching the queries that actually hit the db - it may be as low as 60/40.What do I do when my upgraded RAID setup isnt fast enough? Is my only option to go QUAD processor ? (We REALLY can't afford this as it looks like its about 4x the price of dual)Thanks alot for the help guys.mike123 |
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MichaelP
Jedi Yak
2489 Posts |
Posted - 2004-08-12 : 22:17:23
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| If your RAID isn't fast enough, you'll need more spindles or possibly you'll need to move to a new architecure (IE SCSI to Fibre Channel).With SQL server, you should upgrade the following things in this order:1. Disk subsystem (When in doubt, go RAID 0/1 with lots of spindles). This is generally one of the best areas to spend money on for SQL server.2. RAM (Try to get enough to put your entire database in memory if it's small enough.)3. CPUHTH!Michael<Yoda>Use the Search page you must. Find the answer you will.</Yoda> |
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derrickleggett
Pointy Haired Yak DBA
4184 Posts |
Posted - 2004-08-13 : 03:54:04
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| Just to add to what everyone is saying. A 3-disk RAID five array is the least optimum solution you can have on RAID five. Generally for RAID 5 you want to get between 5-7 disks per array. Anything under this kills you on your parity writes. Anything over this begins to overburden the parity drive. I would probably go with RAID 10 here and partition off 15-30gb for the OS, or go for two RAID 1 arrays. It would be better to get more drives if you can afford them though. A lot of this depends on what kind of cache your controller has, how much RAM you have, size of databases and transactions, what you IO is, etc.MeanOldDBAderrickleggett@hotmail.comWhen life gives you a lemon, fire the DBA. |
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RAID Array