Greg 'groggy' Lehey
grog at FreeBSD.org
Sun Mar 30 15:15:16 PST 2003
On Sunday, 30 March 2003 at 18:00:01 +0200, Lukas Ertl wrote:
> On Sun, 30 Mar 2003, Chuck Swiger wrote:
>> Lukas Ertl wrote:
>> [ ... ]
>> Also, what tasks you intend to use the RAID filesystem for are critical
>> to consider, even if the answer is simply "undifferentiated
>> general-purpose storage". In particular, RAID-5 write performance is
>> going to be slow, even with RAID hardware support which offloads the
>> parity calculations from the system CPU(s). RAID-5 is best suited for
>> read-mostly or read-only volumes, where you value cost more than
> Ok. But I still don't understand why RAID 5 write performance is
> _so_ bad.
That's certainly something to investigate.
> The CPU is not the bottle neck, it's rather bored. And I don't
> understand why RAID 0 doesn't give a big boost at all.
What can it do? You're only writing one file at a time.
> Is the ahc driver known to be slow?
This is definitely not a driver performance issue.
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