CentOS - Aug 2007 - Hot swap SATA?

Should it be possible to hot-swap SATA drives with Centos5?  It doesn't 
seem to work on my system.  Removing an unmounted drive locked the 
system up, and leaving one out at bootup makes the devices change names 
and keeps grub from finding /boot on a scsi drive that is shifted up.

-- 
   Les Mikesell
    lesmikesell at gmail.com

On 8/21/07, Les Mikesell <lesmikesell at gmail.com>
wrote:
> Should it be possible to hot-swap SATA drives with Centos5?  It doesn't
> seem to work on my system.  Removing an unmounted drive locked the
> system up, and leaving one out at bootup makes the devices change names
> and keeps grub from finding /boot on a scsi drive that is shifted up.
Depends on the SATA controller, but yes. If the controller allows, you
can hotswap sata drives.

-- 
During times of universal deceit, telling the truth becomes a revolutionary act.
George Orwell

Just to add my 5 cents (centos 5 cents that is har har)...

I have several plain jane seagate sata drives, connected mostly to nforce4
sata (module sata_nv)  controller, and a few connected to a silicon image
controller (sata_sil) ... hot swap is a non issue for me.  All my drives are
part of MD raid sets - I down the drive using mdadm, and then just pull it
from the chassis (Supermicro 5 drive chassis).  Adding a new drive is
equally easy, just slide it into the chassis and use mdadm to add it to an
array.

Gordon


On 8/21/07, Les Mikesell <lesmikesell at gmail.com>
wrote:
>
> Should it be possible to hot-swap SATA drives with Centos5?  It doesn't
> seem to work on my system.  Removing an unmounted drive locked the
> system up, and leaving one out at bootup makes the devices change names
> and keeps grub from finding /boot on a scsi drive that is shifted up.
>
> --
>    Les Mikesell
>     lesmikesell at gmail.com
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
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On Tuesday 21 August 2007, Feizhou wrote:
> Les Mikesell wrote:
> > Jim Perrin wrote:
> >>> Should it be possible to hot-swap SATA drives with Centos5? 
> >> Depends on the SATA controller, but yes. If the controller allows,
you
> >> can hotswap sata drives.
> > How are the names supposed to work when one may be missing at bootup
and
> > added later?
> I thought the system would just assign the next available /dev/sdx?
> Then there was the post about wanting to be able to pull a SATA/eSATA
> disk in and have the system automatically mount whatever filesystem is
> on the disk...
That was mine.  Still working on it.

As to the hardware support, the definitive answer is found at 
www.linux-ata.org  

As to device naming, use LABEL= to fix that.  SCSI device naming on Linux 
stinks.  

I'm dinking around with a Ubuntu install right now that is giving me fits 
because of linux PCI/SCSI weirdness.  The boot drive (as set in the BIOS) is 
probed by the kernel as /dev/sdc.  Fun.  The setup has two 80GB drives in MD 
RAID1 (200MB /boot on /dev/md0, and 77GB / on /dev/md1, both on the same 
drives) and four 250GB drives in 3-disk RAID5 with a hotspare.  The drives 
are spread on three two port controllers (no, I don't have a four or six
port
controller handy, not an option in this case).  Still working grub to get the 
thing to boot.... 

LABEL= does actually have its uses; I migrated a filesystem on a CentOS 4 VM 
running on one of our two VMware ESX beasts (2x Dell 6950, 4x dual core 
Opterons, 32GB RAM each, dual 4Gb/s fibre-channel to 2x EMC CLARiiON 
CX3-10c's with 20TB each) from the internal 3x300GB RAID to a 1.95TB LUN on 
the CX3.  By using LABEL=, I was able to blow the drive away in VI Client on 
the VM, and boot right up without device ordering problems.

But I have also been bitten by the 'LABELs are the same on cloned disks'
fun
and games....

What I'm currently doing with the eSATA deal is having an entry in fstab,
set
to noauto, and using LABEL=, and an icon in KDE to mount it on the desktop.  
it is not seamless; unmounting is much more of a chore, as KDE has fun with 
the icon, doesn't enable the context menu 'safely remove' (aka,
unmount)
option, etc.  But it's better than nothing.  Just haven't had time to
see how
to enable SCSI removable support (dig through the udev and hotplug stuff 
sometime and you'll see what I mean) in libata as yet.  With SCSI removable 
support (which usbstorage implements, which is why it works) the system Just 
Works properly.
-- 
Lamar Owen
Chief Information Officer
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu