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To: ZC Wong <zcwong@acm.org>
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Cc: sos@FreeBSD.ORG, freebsd-hardware@FreeBSD.ORG
Subject: Re: Write cache for pst (Promise SX6000 RAID)?
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ZC Wong wrote:
> I've got a Promise SX6000 RAID card and the pst driver works without any 
> configuration under a GENERIC kernel came with 6.0-RELEASE.
> 
> The problem is the write caching at OS level, it doesn't look like any 
> data is cached by the OS before it's written (even if there's plenty of 
> free mem).
> 
> Is there any chance I can get the pst driver work like /dev/ad* in term 
> of caching?

Caching at OS level ??
There is no difference in how ATA and pst handle that, in fact the 
driver has nothing todo with caching, thats up to the upper layers not 
the device driver..

> Also there seemed to be a bottleneck of 50MB/s whatever how much hard 
> drives I connect to the array(RAID 0)?

Thats a feature if the sx6000 HW, it cant do more than about 60Mb/s but 
this depends on blocksize etc, so 50Mb/s for your case might be the 
limit for that setup...

-Søren