Re: CentOS 5.5 does not recognise SAS drives with LSI 1068E Controller

[Les Mikesell <lesmikesell@xxxxxxxxx>]

On 3/10/2011 12:19 PM, John R Pierce wrote:
>
>>> That controller doesn't really support RAID, what you're getting is
>>> commonly called FakeRAID
>> If you are referring to the 1068E, that is completely wrong.
>
> They do have basic hardware raid, with an embedded control processor,
> but they don't have any battery back write-back cache, which negates any
> real advantages of hardware raid.

How important is the card-level battery if you have a UPS and a scheme 
to monitor it and do a graceful shutdown before it fails?

> I always configure those as simple
> SAS controllers and use the OS native software raid (mdraid mirroring in
> the case of Linux).  I also almost never use any raid level above raid1
> or 10 (mirror or stripe/mirror).

I like raid 1 myself because you can recover data from any remaining 
disk after a failure and software raid because you can use any vendor's 
controller for that recovery, but if you use raid 5 you might want the 
hardware controller to do the parity computation work.

-- 
   Les Mikesell
    lesmikesell@xxxxxxxxx
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