RE: Udev rules for SATA drives

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> unfortunately
> > removing one of the drives causes the kernel to shuffle the drive
> > assignments up (rather than simply leaving a gap as with IDE).  IE.
> > normally I will have sda-sdc... if I remove the second drive, my goal
> > is to have sda and scd (with sdb missing) instead of having sda, sdb
> as is assigned by default.

> What I suspect is happening when you remove the second drive is that
> your rules are creating /dev/sda and /dev/sdc, while the default rules
> are creating /dev/sdb that is the same hardware as /dev/sdc that you
> created. If you removed the third drive, then the forth would probably
> end up as both /dev/sdc and /dev/sdd.

That's exactly what is happening.

> The other thing you could try is to change the names from sda%n to
> something like raid%n and then configure the RAID driver to use these
> names.

This seemed like such a simple and promising solution but unfortunately is a
no-go.  Booted up from the install CD to test... manually created the device
nodes for the raid* devices, even deleted the sd* nodes just to make sure
:-)  Used mdadm from the commandline to create a raid array specifiying the
/dev/raid* nodes as the member drives.  No errors... that's a good thing :-)
Then took a peek at /proc/mdstat and there it is happily syncing the
array... with member devices sda1, sdb1 and sdc1.

The only thing I can figure is that the MD driver is looking back to the
kernel (and/or /sys)... since no matter what /dev nodes I use dealing with
the array it seems to always translate that back into an SD device.

>From my reading today it appears that the FreeBSD folks have at least
thought of this scenario and have (albeit through a kernel compile switch)
the ability to have a fixed scsi device mapping.  But I've seen no mention
of anything similar in Fedoraland.  

At this point I think I'm just going to have to keep a second spare SATA
drive laying around to make sure that if anything goes badly wrong enough
that any of the drives decide to check themselves off of the bus that I have
something to stick in its place to keep the drive order constant.  :-)

Unfortunately this seems to be one of those things that SATA has inherited
SCSI... though I still can't make a case in my mind about why it ever would
have been a desirable behavior to have one's devices rearrange themselves
:-) 

Cheers,
>>>>> Mike <<<<<
    


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