Sven,

This looks like a well known problem with 9500 series cards with the 9.2 series firmware and battery backup units.  To quote from a recent submission to the linux-ide-arrays list:

"There are some bad BBUs out there that never get fully charged.  The 
9.2 firmware recognizes that the BBU isn't fully charged and disables the 
write cache, trashing performance.  This doesn't happen with 9.1.5.2 
since, well, it pretty much just ignores the BBU."

I believe you can RMA the BBUs for new ones. 

The original post goes on about another issue which might affect your setup - I'll forward you the original.

Martin.

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]] On Behalf Of Sven Sternberger
Sent: Thursday, July 14, 2005 6:46 PM
To: [log in to unmask]
Subject: OT: 3ware-9xxx on 64bit


Hello!

maybe slightly ot

I hardly try to get an 3w-9xxx 12 port sata raid on an tyan-2882 (dual opteron 246, 4gb ram) to work well on an SL 4.

my problem is that i have a write-rate something about 20mb/s. I already tried it with:

blockdev -satra 16384
3ware FW Update on 9.2.1
Kernel Update 2.6.12.2
numa off
complety other distribution ubuntu warty (64bit version)

I ran tiobench and bonnie++ on ext3 and xfs, but I always get only 20mb/sec. In iostat I can see that I have about 80-90% iowait.


I double checked that I switched on the wrtite cache.

Maybe somebody has an idea

regards!

sven