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Re: Lockups and other trouble using large disks, raid(4), cgd(4), dk(4)

On Fri, Nov 21, 2008 at 01:12:18AM +0100, Nino Dehne wrote:
> OK, that went nowhere. I decided to try without cgd. I created an FFS
> partition covering the whole raid0 using newfs -O 2 -b 65536 /dev/dk5
> after changing the partition type of dk5 from cgd to ffs. The 64K
> block size is necessary to match the 32 sectors stripe size of the RAID5.
> Other values lead to abysmal write performance.

I do not doubt that under some condition you measured poor write performance.
However, the explanation above is simply wrong.

Hint: how many kilobytes is 32 512-byte sectors?  But there's more wrong
with the explanation than that.


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