RAID

[Anders Karlsson]

On 1/1/06, 'Forum Post <ulist at gs1.ubuntuforums.org> wrote:
>
> FGMYI:
>
> I don't like to xpost, but I came across your discussion in ML while
> searching all things I could find about dmraid.

No problem :)

> Several years ago we did some tests with md. Finally we found that only
> a real HW-RAID scsi controller is robust enough for a production level
> system. What I am wondering is that ASUS PSCH-L mainboard contains a
> Promise PDC 20319 SATA RAID controller (having one of those, here).
> This MB is built into the server ASUS AP-130. It has been sold to us as
> an 'entry level production system'.

If you intend running a production system that needs four or five
nines reliability, then you need a proper HW RAID solution. Any of the
el-cheapo fakeraid (Siimage, Promise etc onboard "raid") is not going
to cut it.

Only a solution where the controller handles the RAID operations, and
you get presented a logical disc will do IMO. Once you start having to
rely on userspace tools to set up the logical drives, you have gone
from production environment to "happy amateur playing at home".

From what I can tell from a quick google, the PDC 20319 SATA RAID is a fakeraid.

If you can, go for a SCSI (or SAS) solution. They are more reliable,
polished and in general "just work". Not to mention that the do do all
the stuff in hardware the way a real RAID controller does. More or
less anything SATA or PATA RAID 0,1,0+1 today is the cheap tat. A real
PATA RAID controller will set you back maybe 300 quid. SCSI RAID about
the same price.

> Because I am not lucky with what I do knowing inbetween:
>
> What controller would you suggest for a real RAID1 SATA hardware
> solution reliably working with RAID1 under Debian?

RocketRAID 1820A RAID (US$230) seems to do real HW RAID, and it does
RAID5 as well. Good signs of a proper RAID controller is battery
backed fast write cache. Price will usually tell you if it is tat or
good stuff. Unfortunately, there is no cheap good solutions....

HTH,

--
Anders Karlsson <trudheim at gmail.com>