poor Raid5 write speed

[Digimer]

On 10-07-27 12:36 PM, William Park wrote:
> Hi all,
>
> My Software Raid5 has lower write speed than a single harddisk.
> I tried copying whole bunch of *.iso
>
>      - from Raid5 to a separate harddisk		-->  130 MB/s
>      - from the separate harddisk to Raid5	-->  110 MB/s
>
> Is this normal?

You're probably seeing overhead from the parity calculations. Last time 
I saw the numbers run, it needed ~6 drives for the benefits of stripping 
to outdo the overhead of parity on software. Of course, this depends on 
a lot of things so use "6" as a rough number.

-- 
Digimer
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