Subject: Re: Four Drive RAID-5 on RAIDFrame Considered Harmful...
To: None <tls@rek.tjls.com>
From: Robert P. Thille <list-netbsd-tech-perform@rangat.org>
List: tech-perform
Date: 10/09/2007 20:22:42
On Oct 9, 2007, at 6:53 PM, Thor Lancelot Simon wrote:
> On Tue, Oct 09, 2007 at 04:59:58PM -0700, Robert P. Thille wrote:
>>
>> I tracked it down to the problem that 2 and 3 are relatively
>> prime :-)
>> Given 4 drives in a RAID-5 setup, you get 3 data blocks per raid
>> stripe,
>> but the filesystem block size Must be a power of 2, so you always
>> have
>> to write at least one partial stripe.
>
> No. Examine the "maxcontig" FFS parameter.
>
maxcontig appears to be obsolete. Looking thru the sources (current
from a month or so ago), I don't think it's used by the kernel/
filesystem, and the options mentioned in postings I found in the
mailing lists don't seem to exist anymore.
Am I missing something?
Thanks,
Robert
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