"E.B. Dreger" schrieb:
>
> Greetings all,
>
> I just had a brainstorm...
>
> I was thinking about database servers with several spindles in a RAID 5
> array. Write performance is inherently disappointing -- which may or may
> not be an issue.
It is. Even RAID 1 is better than RAID 5 _for_database_use_. For added
security, have run a RAID 10 array (basically, a mirrored stripe set).
> Would it be worth the trouble to design an "intermediate" cache, whereby
> data are quickly written to a spool disk, then to the final destination?
> Sort of like softwares that cache CDROMs on HDD...
>
> My gut feel is that this would be more trouble than it's worth, would not
> net any overall performance*reliability (expressed as a product) gain, and
> that one might actually realize a p*r decrease.
IMHO it would speed up your DB significantly to have it a) run on a RAID
10 array and b) have it run on the raw disk. Two layers of lag reduced
(well, for reads it is possibly only one layer).
HTH
-Christoph Sold
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