[CentOS-virt] Slightly OT: FakeRaid or Software Raid

Wed Dec 2 21:49:18 UTC 2009
Ben M. <centos at rivint.com>

Thanks. The portability bonus is a big one. Just two other questions I 

- Raid1 entirely in dom0?
- Will RE type HDs be bad or good in this circumstance? I buy RE types 
but have recently become aware of the possibility where TLER 
(Time-Limited Error Recovery) can be an issue when run outside of a 
Raid, e.g. alone on desktop machine.

I do have a utility where I can change the HDs firmware setting to get 
turn it off or on for either Read or Write delays.

Christopher G. Stach II wrote:
> ----- "Ben M." <centos at rivint.com> wrote:
>> I have had great luck with nvidia fakeraid on RAID1, but I see there
>> are 
>> preferences for software raid. I have very little hands on with full 
>> Linux software RAID and that was about 14 years ago.
> MD RAID. I'd even opt for MD RAID over a lot of hardware implementations. This writeup summarizes a bit of why:
> http://jeremy.zawodny.com/blog/archives/008696.html
> Hardware RAID's performance is obviously going to be better, but it's only worth it if you *need* it (more than ~8 disks, parity). If you're just doing RAID 0, 1, or 10 in a single box and you're not pushing it to its limits as a DB server or benchmarking and going over it with a magnifying glass, you probably won't notice a difference in performance.
> I'll take fewer moving parts and portability.
> As someone already said, dmraid is done in software, too. "Fakeraid" is basically the same as MD RAID, but with an extra piece of hardware and extra logic bits to fail.