smartd and RAID: Was: Re: What is smartd?

Ralf Corsepius rc040203 at freenet.de
Fri Aug 13 11:44:42 UTC 2004


On Fri, 2004-08-13 at 10:58, Ross Macintyre wrote:
> Erik Espinoza said:
> > It should be noted that smartd will not work on scsi drives that are
> > part of a hardware raid array. Those device are masked by the raid
> > controller and accessed very differently.
> 
> which is not what Ralf Corsepius said in a previous message, when I asked
> that precise question:
> 
> Ralf Corsepius said:
> * > Sorry for butting in here, but is there any use in having smartd running
> * > if one has a SCSI RAID system?
> * Of cause; smartd/SMART try to monitor hard-disk sanity, no matter if
> * using RAID or not.
> 
> so who is right?
Neither and nor ;)

SMART is implemented into a hard-disk's controller (into the board on
top of the hard-disk; not into the hard-disk controller on your
motherboard).

smartd is a userspace program that tries to communicate to the SMART
support on each single hard-disk.

Anything else inbetween (busses, BIOS, controllers, kernel, etc.) can
interfere. So if a hard-disk has SMART support on-board, and if you can
access the hard-disk's directly, you'll probably also be able to use
smartd.

If not, you'll probably not be able use smartd/SMART.

Here come HW-RAID controllers ...

Yes, they might prevent you from using smartd, they might have an
option/mode to access each disk individually, they might internally
apply SMART to monitor disks themselves, they might let you pass though
SMART commands to individual disks, they might have SMART implemented
themselves ...

I.e. chances are not unlikely smartd will not work with HW-RAID
controllers. With SW-RAIDs and individual disks, it works.

Ralf







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