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Re: [linux-lvm] Apparent performance degradation for each PV with striping



On Monday 19 March 2001 14:34, S. Michael Denton wrote:
> I tend to agree.  In general software RAID will bog the system down
> and if performance is key, you should take the load off the CPU
> whereever possible.  The obvious conclusion with data volumes is to
> use a hardware RAID controller, beit SCSI or IDE... I've used both
> SCSI raid controllers and the IDE promise raid controller with good
> results.  The other thing that may be killing your performance is IO
> contention.  Check for other highly-used devices on the same PCI
> bus... on PCs there are quite a few points of possible contention.

That really depends on the type of card.  There are many hardware RAID 
devices out there that have significant limits on performance (they give less 
performance from an array of 10000rpm Ultra2-SCSI drives than you expect from 
a single ATA drive).

Hardware RAID controllers that have a CPU that is less than 100MHz in speed, 
or that don't have battery backed cache for write-back caching tend to 
deliver less performance than you hope for.

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