Simon Banton wrote:
At 11:16 -0400 14/9/07, Ross S. W. Walker wrote:
Yes, a write-back cache with a BBU will definitely help, also your
config,
The write-cache is enabled, but what I've not known up to now is that
the absence of a BBU will impact IO performance in this way - which
seems to be what you and Feizhou are saying. Is there any way to tell
the card to forget about not having a BBU and behave as if it did?
Short of modifying the code...I do not know of any.
The main problem here is the latency when under IO load not the
throughput (or lack of). I don't care if it can't achieve 300MB/s
sustained write speeds, only that it shouldn't bring the machine to its
knees in the process of getting 35MB/s.
SATA 7200RPM disks are not exactly fantastic at random i/o. The cache
only boosts writes in a significant way and less so for reads. Maybe you
could consider RAID10.
That way, them 7200RPM disks are a match if not better than hardware
raid with BBU cache for a mirror of scsi drives.
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