graid fresh install

[Alexander Motin]

Mike Tancsa wrote:
> On 8/5/2011 12:01 PM, Mike Tancsa wrote:
>> and mount it. However, speeds seem a bit slow, but I am not sure if
>> thats to be expected.
>>
>> i5# dd if=/dev/zero of=/mnt/test bs=1024k count=100
>> 100+0 records in
>> 100+0 records out
>> 104857600 bytes transferred in 13.996080 secs (7491926 bytes/sec)
>> i5#

That's odd. It should not be that bad. Here is my RAID1 system:
%dd if=/dev/zero of=qqq bs=1m count=100
100+0 records in
100+0 records out
104857600 bytes transferred in 1.359660 secs (77120448 bytes/sec)

Here is RAID0 of two SSDs:
> dd if=/dev/zero of=qqq bs=1m count=1000
1000+0 records in
1000+0 records out
1048576000 bytes transferred in 1.148323 secs (913136762 bytes/sec)

Can you check whether disk read/write caches are enabled with
`camcontrol identify adaX`? If you prefer to have write caches disabled,
you should have load that creates multiple concurrent I/O requests to
saturate disk bandwidth.

> One extra bit of oddness with graid, is that if I disable the RAID in
> the BIOS and boot up the disks just with plain old AHCI, graid still
> works. Is that a quirk of the BIOS, or does it generally work that way?

graid just reads on-disk metadata. AHCI/RAID modes set by BIOS affect
only whether RAID BIOS will be running. From the hardware or OS driver
level they are identical, except chip PCI IDs, that is not checked now.

-- 
Alexander Motin