Re: IDE hotplug support?

[Martin Dalecki <dalecki@evision-ventures.com>]

Uz.ytkownik Jakob Østergaard napisa?:
> On Thu, May 02, 2002 at 09:26:38PM +0100, Alan Cox wrote:
> 
>>>>=20
>>>>8 x 130MBy/s >>>> PCI bus throughput... I would rather recommend
>>>>a classical RAID controller card for this kind of
>>>>setup.
>>>
>>>Because RAID controllers do not use the PCI bus ???    ;)
>>
>>The raid card transfers the data once, software raid once per device for
>>Raid 1/5 - thats a killer.
> 
> 
> For RAID-1 it's a killer (for writes), I agree.
> 
> But I really doubt it would be so horrible for RAID-5 - after all, it's only
> one extra block (the parity block) for each N-1 blocks written (for an N disk
> RAID-5).  The penalty should be less, the more disks you have in the array.
> 
> But seriously, has anyone out there ever seen a hardware RAID controller with
> a *sustained* RAID-5 thoughput of more than 60 MB/sec ?   Not that I think it
> is impossible, but I've never heard about it.  Enlighten me, please, and not
> with marketing numbers...


Go to Sun hardware and you will see it quite frequently even on a simple
E450 equipped with an external RAID box. I saw them frequently enough in
sar accounts when the system was configured to trash on a swap
partition, which resided on such a RAID.

64 bit buses win here by a huge margin.