RAID-5 and database servers

Jason Edgecombe jason at rampaginggeek.com
Fri Mar 12 11:44:45 CST 2010


John G. Heim wrote:
> From: "Jefferson Ogata" <poweredge at antibozo.net>
>   
>> *Again*, this is why if you have particular performance requirements,
>> you should consult with your database vendor to determine what bandwidth
>> and IOPS you need, and benchmark your gear using different RAID configs.
>> You may find that RAID 5 is just fine performance-wise, and you can get
>> around 1.7 times the storage capacity with the same rack space, heat,
>> and power load over RAID 10. Asking here you're just going to get people
>> parroting Oracle's stale recommendations and speculating wildly without
>> knowing anything about your workload.
>>
>>     
>
> Well, its not really practical to suggest that I consult with my vendor. My 
> whole budget is $6000. This is just the Math Department at the University of 
> Wisconsin. I mentioned in my original message that our databases consist 
> primarily of spamassassin bayesian rules and horde3/imp web mail. Those do a 
> lot of updates -- well, a lot by our standards. Every time a spam message 
> comes in, it it is added to the bayesian rule set for the user. I'm going to 
> say that typically each user gets 100 spam messages a day and there are 200 
> users. But each new rule consistes of several table updates. Even so, its 
> not like we're ebay.
>
> Anyway, speed of updates is critical because we can't have the mail system 
> getting bogged down by database updates. I put the bayesian rules in a mysql 
> DB in the first place because it was getting bogged down saving bayesian 
> data to bbm files on the mail server.
>
> I just want to make sure that I'm not setting myself up for a disaster.
>   
If writes are an issue and the DB can fit in RAM and you don't mind
losing a few writes, then you might try mounting the DB or bbm files in
a tmpfs filesystem  (aka ramdisk) with a sync to disk every 5 minutes or
so. I read an article about someone doing that for ganglia data because
the number of transactions was killing them.

Jason



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