vinum performance

[Greg 'groggy' Lehey]

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
>> performance.
>
> 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.

Greg
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