[LAU] Hard drive for "/" should be also 7200 rpm?

[Hakan Koseoglu]

On 20 February 2012 03:04, Al Thompson <althompson58 at gmail.com> wrote:
> I'm curious about about much doing RAID in software may impact CPU load
> and overall system overhead.
There's an impact but less than most people expect to see. If you
really insist, you need to have a good (at least RAID-1 supporting)
card but you must avoid any fakeraid implementations (where the real
work is still done by CPU but it is not that easy to migrate, I
haven't used one for a decade but they're still around - the first
ever SATA interface card I got had a fakeraid implementation).
Mirroring via mdadm is usually good enough. If you want to try, just
plug a 2nd disk and build an array, it's always possible to
(carefully) dismantle the array later and go back to single disks. Day
job mainly involves around high performance OLTP databases, we never
use software raid since the servers we use always have decent SAS
interfaces with good RAID support. Use of software RAID rarely comes
up but sometimes it does and we lose about 1-2% performance overall.