3ware and scsi ids

3ware and scsi ids

[Deas, Jim]

I am currently using 3wares products to create 2T raids.
To increase performance on my NAS type boxes I am
using software raids.
 My problem relates to a falure of a IDE drive.
Once a drive fails the next boot of the machine remaps all scsi ids.
so /dev/sda-adi becomes /dev/sda-sdh.
In short, if /dev/sdb dies, all raids become bad as all scsi ids
shift down making my raidtab file now point at the wrong drives.
(I assume this will also be a possible problem when I use
my USB dongle to update software.)

 Is there a way to hard assign logical /dev/sd(x) in the driver
so they will always map the same ide port on the 3ware controllers?
3ware is no help on this. They say it is the bios/system and they
have no control over this.

Thanks
J. Deas

Re: 3ware and scsi ids

[Alan Cox]

On Maw, 2003-06-03 at 19:05, Deas, Jim wrote:
> In short, if /dev/sdb dies, all raids become bad as all scsi ids
> shift down making my raidtab file now point at the wrong drives.
> (I assume this will also be a possible problem when I use
> my USB dongle to update software.)

Yes that sometimes comes up, along with a wonderful variant where 
USB cameras beat the PCI sound card to being first sound device
> 
>  Is there a way to hard assign logical /dev/sd(x) in the driver
> so they will always map the same ide port on the 3ware controllers?
> 3ware is no help on this. They say it is the bios/system and they
> have no control over this.

Correct.

The vendor Linux systems mostly support mount by label so you can
avoid using anything but the file system label to find a disk if
something vanishes.

So you'll see lines like this in /etc/fstab

LABEL=/boot             /boot                   ext3    defaults       1
2

RE: 3ware and scsi ids

[Deas, Jim]

I have never seen labels in the raidtab.
fstab yes. raidtab no. Is it possible?
Is this a better solution than LVM?
LVM seem to insert yet another layer.
I would like to avoid that if possible.

JD


-----Original Message-----
From: Alan Cox [mailto:alan@lxorguk.ukuu.org.uk]
Sent: Tuesday, June 03, 2003 12:58 PM
To: Deas, Jim
Cc: linux-scsi@vger.kernel.org
Subject: Re: 3ware and scsi ids


On Maw, 2003-06-03 at 19:05, Deas, Jim wrote:
> In short, if /dev/sdb dies, all raids become bad as all scsi ids
> shift down making my raidtab file now point at the wrong drives.
> (I assume this will also be a possible problem when I use
> my USB dongle to update software.)

Yes that sometimes comes up, along with a wonderful variant where 
USB cameras beat the PCI sound card to being first sound device
> 
>  Is there a way to hard assign logical /dev/sd(x) in the driver
> so they will always map the same ide port on the 3ware controllers?
> 3ware is no help on this. They say it is the bios/system and they
> have no control over this.

Correct.

The vendor Linux systems mostly support mount by label so you can
avoid using anything but the file system label to find a disk if
something vanishes.

So you'll see lines like this in /etc/fstab

LABEL=/boot             /boot                   ext3    defaults       1
2

RE: 3ware and scsi ids

[Alan Cox]

On Maw, 2003-06-03 at 23:16, Deas, Jim wrote:
> I have never seen labels in the raidtab.
> fstab yes. raidtab no. Is it possible?
> Is this a better solution than LVM?
> LVM seem to insert yet another layer.
> I would like to avoid that if possible.

Ah sorry I misunderstood your original message slightly.

raidtab doesn't have any labels. This might be useful
however. The Dell guys wrote a tool that generates consistant
naming using device serial info

	http://www.lerhaupt.com/devlabel/

Re: 3ware and scsi ids

[Friedrich Lobenstock]

Deas, Jim wrote:
> I am currently using 3wares products to create 2T raids.
> To increase performance on my NAS type boxes I am
> using software raids.
>  My problem relates to a falure of a IDE drive.
> Once a drive fails the next boot of the machine remaps all scsi ids.
> so /dev/sda-adi becomes /dev/sda-sdh.
> In short, if /dev/sdb dies, all raids become bad as all scsi ids
> shift down making my raidtab file now point at the wrong drives.
> (I assume this will also be a possible problem when I use
> my USB dongle to update software.)
> 
>  Is there a way to hard assign logical /dev/sd(x) in the driver
> so they will always map the same ide port on the 3ware controllers?
> 3ware is no help on this. They say it is the bios/system and they
> have no control over this.

You'd better use mdadm instead of the raidtools.

The config file for mdadm looks like this:
# cat /etc/mdadm.conf
DEVICE /dev/hd* /dev/sd*
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=52094036:b2e9cf8b:4267c923:750757da

So you do not have to worry about which drive gets assigned which
scsi id.

A
    /sbin/mdadm --assemble --scan
will do the trick.

Get it at http://www.cse.unsw.edu.au/~neilb/source/mdadm/

-- 
MfG / Regards
Friedrich Lobenstock
____________________________________________________________________
Friedrich Lobenstock                       Linux Services Lobenstock
URL: http://www.lsl.at/                         Email: fl@fl.priv.at
____________________________________________________________________