raid or not raid

[John Nielsen]

On Thursday 24 May 2007 06:30:06 am kalin mintchev wrote:
> so nobody on this list knows anything about raid?
> wrong list?
>
> > hi all..
> >
> > i have a box in a remote hosting facility that claims that the machine
> > has two discs raided in it but df and fstab show only one disc with a
> > bunch of slices.
> > under devices there is another name - ad6 - but it's not mounted
> > anywhere. the one i see both in df and the fstab is ad4 with one big
> > slice and different partitions....
> >
> > they insist there are 2 raided discs in tha machine. the os is 5.4 and i
> > think at that point the raid drivers were still considered
> > 'experimental'.
> >
> > it makes sense to me that if i don't see a second drive in the fstab
> > there isn;t any mounting which means that there is no raid going on...
> >
> > is there any other way i can make sure if raid is actually on?
> > would there will be any logs somewhere?
> > the machine has been up for about 2 years and the dmesg is long gone...

My guess would be that it's not actually doing RAID. "Real" hardware RAID 
controllers either require their own drivers (twe, for instance shows disks 
as twed0, etc) or present disks as SCSI devices (e.g. da0). ATA pseudo-raid 
hardware supported by FreeBSD's ata(4) driver shows both the raw disks (ad4, 
ad6, etc) AND an "array" device like ar0.

If RAID was set up in the BIOS then FreeBSD is probably ignoring it, perhaps 
because ata(4) doesn't grok the metadata format used by the RAID card.

If I were you I would aim to migrate to gmirror RSN.

JN