On Mon, Aug 30, 1999 at 11:04:08AM -0400, Mike Black wrote:
> But this is doing disk "reads" not "writes". It shouldn't need to read from
> both disks.
>
> From
> http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/Software-RAID.HOWTO-2.html#ss
> 2.3
>
> For RAID1:
> Read performance will usually scale close to to N*P, while write performance
> is the same as on one device, or perhaps even less. Reads can be done in
> parallel, but when writing, the CPU must transfer N times as much data to
> the disks as it usually would (remember, N identical copies of all data must
> be sent to the disks).
>
> I should expect at least the same performance (when disks are on the same
> bus) -- that's why I'm confused. I would actually expect better performance
> given that the limit is the disk i/o speed and not the data bus. If disks
> were on seperate buses I would expect better performance.
Because the disks are on the same bus, only half the number of requests/sec can
reach each drive.
Put each disk on it's own bus, and you'll see a change (I almost promise :)
................................................................
: [EMAIL PROTECTED] : And I see the elder races, :
:.........................: putrid forms of man :
: Jakob Østergaard : See him rise and claim the earth, :
: OZ9ABN : his downfall is at hand. :
:.........................:............{Konkhra}...............:
