FreeBSD 9.0 & LSI MegaRAID SATA problem

Wojciech Puchar wojtek at
Tue Jul 10 11:22:47 UTC 2012

On Tue, 10 Jul 2012, Bosko Radivojevic wrote:

> On Tue, Jul 10, 2012 at 12:26 PM, Wojciech Puchar
> <wojtek at> wrote:
>> what other do you expect with no mirrors created yet?
> But mirror (raid10) array is created through LSI MegaRAID BIOS. I'm

if it is RAID10 i assume you have 4 disks.

> trying to replicate behaviour from FreeBSD 8.3 (array created through
> RAID BIOS, seen as a device in OS).
BIOS raid is not compatible with gmirror RAID.

backup and restore.

Actually i would recommend creating it as two RAID1 (gmirror) devices and 
spreading data. it is safer and..if you can spread data well... faster.

"BIOS" RAID usually use far too small block sizes, to be "better" on 
windows benchmarks that shows linear read speed.

except specialized uses it is no improvement under unix.

What you need is to spread DIFFERENT I/O operations from different task to 
different heads.

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