On Wednesday, 28 March 2001 at 1:40:27 +0100, Brian Somers wrote:
>> On Tuesday, 27 March 2001 at 9:39:36 +0100, Brian Somers wrote:
>>>> On Tuesday, 20 March 2001 at 11:11:44 -0600, Michael C . Wu wrote:
>>>>> [Lengthy email, bear with me please, it is quite interesting.
>>>>> This box averages 30.0 load with no problems.]
>>>>>
>>>>> <snip>
>>>>>
>>>>> Average file size is about 4K. /home/bbsusers* is on a vinum
>>>>> stripe'd volume with 3 Ultra160 9G 10000RPM drives on sym0 at stripe
>>>>> size 256K, Greg: I know this should be a prime number,
>>>>
>>>> No, there's no requirement for it to be a prime number. The only
>>>> problem is that with 32 MB cylinder groups and a power of two stripe
>>>> size and subdisk count, you end up with all the superblocks on one
>>>> subdisk, which is a performance issue. Choose the stripe size so that
>>>> the superblocks are roughly evenly distributed.
>>>
>>> A performance issue ? Surely you've misspelt ``reliability'' ?
>>
>> I don't see a reliability issue here.
>
> I believe the only issue with having all your superblocks on one disk
> is a reliability thing - if you lose the disk you lose your
> superblock(s).
Ah. Lose part of your file system and you lose your file system.
Vinum has other ways of making up for that problem.
> Surely the only performance problem would be that of locality - if
> you use the partition a bit, that ``problem'' should go away though.
No, under normal circumstances all metadata updates would go to the
same disk, since they're just behind the superblock.
Greg
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