One of the things I REALLY like about my Baydel RAID units
(besides the tremendous performance that happens to not be
priced like the Clariions they compete with) is that I can
get stats from the box.

And I can use that information to adjust stripe size.

RAID storing email data performs better with different 
settings that the box backing a Sybase database.

And those are different than boxes serving general home
directories and boxes serving enormous numbers of photos.

RAID tuning is also related to filesystem tuning via newfs.


On disks, you really home that the IDE drives are not using that
cache for WRITES.  There have been some that do that, but it's
a REALLY bad idea without a full NVRAM thing with it.  You lose
power and data that the disk SAID what committed is lost in the
RAM.  No, those 8MB caches should be for reads.

Quoting Jukka Marin (jmarin@pyy.jmp.fi):
> On Fri, Sep 20, 2002 at 11:40:43PM +0200, Wojciech Puchar wrote:
...
> I created the label manually and then used disklabel -r -w raid0 foo
> 
> I guess I should have obeyed the man page..
> 
> Do you know what values I should use in /etc/raid0.conf for fast disks?
> I'm using
> 
> START layout
> # sectPerSU SUsPerParityUnit SUsPerReconUnit RAID_level_1
> 128 1 1 1
> 
> START queue
> fifo 100
> 
> for a RAID1 system, but extracting tar balls feels very slow.  My disks are
> 120 GB WDC 7200 rpm disks with 8 MB caches and when I tested the read speed
> with dd (from raw device), I got 49 MB/s from both disks _simultaneously_.
> I think the disks are fast, but RAID is killing the performance.  My CPU is
> a 700 MHz Athlon in this case.