Messages in this thread | | | Date | Thu, 2 May 2002 23:13:59 +0200 | From | Jakob Østergaard <> | Subject | Re: IDE hotplug support? |
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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...
> > > By the way, has anyone tried such larger multi-controller setups, and t= > > ested > > the bandwidth in configurations with multiple PCI busses on the board, = > > versus a > > single PCI bus ? > > With 2.4 yes. With all the 2.5 changes no.
Did you get any speedup ? Were you close to PCI bus saturation in the one-bus scenario ?
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