Hi Konstantin Olchanski!

 On 2015.05.15 at 18:58:04 -0700, Konstantin Olchanski wrote next:

> in your case, the vendor says "enterprise" and "trim" and "rapid",
> but is it any better than plain mdadm software raid, better by what criteria?

Um, it is still handled by mdadm in Linux. It's just different on-disk
format for defining RAID type.

There are some limitations compared to default format used by mdadm
(e.g. inability to RAID partitions, you can only RAID whole drives) and
there are some benefits, main being able to set up disks in RAID and see
RAID type directly from firmware tool, which understands this format.

RST/RST-E differences and TRIM support only applies when using Intel
software RAID driver on windows, for Linux it makes no difference, since
the same MD driver handles it anyway. Disk format is the same for RST
and RST-E. "E" is just something like feature flag for windows driver.

In general, it makes no difference whether to define raid in RST
firmware or use standard mdadm format. It's only metadata block that's
would be different. Modern installers, including SL6/SL7 anaconda
support format defined by RST firmware and will show you disks in RAID
exactly as if you created software RAID from the installer. There will
be no difference after installation, except for mdadm showing that
metadata is in different format.

IMHO unless one is planning to move these disks to hardware RAID Intel
controller (which understands this metadata format and will handle this
RAID in hardware), there is no point in creating RAID in RST.

-- 

Vladimir