Optiplex 755 RAID 1 logical drive configuration ignored by
FreeBSD 9.0-R installation
wojtek at wojtek.tensor.gdynia.pl
Sat May 19 14:31:11 UTC 2012
> I used 'hardware RAID' because that is -precisely- how the OP described
> their equipment.
unfortunately this is true - it is DESCRIBED as such. lie is standard tool
in todays IT marketing.
What are facts:
- very few controllers actually have some RAID support. those usually have
onboard RAM in substantial amount and preferably - battery backed.
- unless you need RAID-5,6 or similar hardware cannot speed it up much.
- gmirror/gstripe in FreeBSD is vastly superior to any RAID including true
hardware ones - if configured properly. unless you treat single-process
sequential read as measure of performance.
even graid5 (from ports) is close to, or even outperform true hardware
RAID, but CPU load is substantial.
- RAID hardware does not allow any flexibility, like partitioning disks
and using different RAID styles for parts. very useful.
- with FreeBSD software RAID you will be able to access your data in every
computer with SATA port.
> And Dell does offer at least one such controller.
Yes true. Actually all recently bought servers i have to manage are Dells
(yes their 24-hour warranty replacement on place actually work!).
And i always make sure no "hardware" RAID is present :), to get best
Actually i told Dell marketer i will be recommending hardware RAID
solution for Dell when he prove it will actually outperform my
software RAID10 setup with same amount of same disks. Still not proved ;)
Of course you have to properly configure both "hardware" and software
The cases where true hardware RAID may help is it's battery backup
write-buffer that consume forced syncs (database commits etc) when they
are common. still if it is an issue it means than database software is
really badly designed if it have to sync constantly. But if there is no
choice, today there are simple solutions like small-size SLC flash drive
or battery backed ramdisk in extreme cases.
> Further, I, personally, have a fairly similar Compaq machine, which has
> hardware RAID, with it's own BIOS (including configuration/setup screens).
what is the chip that you say it is hardware RAID?
I dare to not believe you, but possibly you are right.
More information about the freebsd-questions