2003-01-17 22:06:17

by Lerhaupt, Gary

[permalink] [raw]
Subject: Devlabel: static device naming via symlinks (improved)

I've added a couple useful features to devlabel (available at
http://domsch.com/linux/devlabel). Of the foremost of these is that it now
includes the usage of Partition UUIDs (as provided by ext2, ext3, xfs, jfs
or ocfs). Since these UUIDs are partition specific, if a partition-level
failure event occurs (eg. you delete /dev/sde6 and /dev/sde7 then becomes
/dev/sde6), devlabel is now smart enough to handle it for the aforementioned
filesystem types. If you aren't using one of these filesystem types or if
there is no filesystem at all, devlabel will then fall back on using SCSI
UUIDs or IDE identifiers as it used before (these support disk-wide
failures, when /dev/sdb6 becomes /dev/sda6).

As well, devlabel now also supports automounting. For example, with a USB
flash reader, you should now add it to devlabel with the --automount option.
If --automount is specified, every time you hotplug your device, it will
check /etc/fstab for an entry containing the symlink that you've added for
this device, and if it finds one, it will automatically mount it. Nice and
simple.

Lastly, you can also now do adds by UUID. This is especially helpful in
shared storage environments. For example, you can add a symlink on the
master node and then add by UUID on all the secondary nodes to ensure that
the same symlink on all nodes points to the same shared storage device
regardless of the device naming scheme of those nodes.

Gary Lerhaupt
Linux Development
Dell Computer Corporation


2003-01-18 16:38:39

by Jeremy Jackson

[permalink] [raw]
Subject: Re: Devlabel: static device naming via symlinks (improved)

I've been using EVMS (http://evms.sourceforge.net and it's snapshot
capability (as well as LVM's I assume) can create "partitions" or
volumes with duplicate fs UUIDs. Perhaps someone using EVMS may not use
devlabel since it includes that functionality, but in the LVM case you
may want to investigate the effect of duplicate UUIDs.

Regards,

Jeremy

On Fri, 2003-01-17 at 17:15, [email protected] wrote:
> I've added a couple useful features to devlabel (available at
> http://domsch.com/linux/devlabel). Of the foremost of these is that it now
> includes the usage of Partition UUIDs (as provided by ext2, ext3, xfs, jfs
> or ocfs). Since these UUIDs are partition specific, if a partition-level
> failure event occurs (eg. you delete /dev/sde6 and /dev/sde7 then becomes
> /dev/sde6), devlabel is now smart enough to handle it for the aforementioned
> filesystem types. If you aren't using one of these filesystem types or if
> there is no filesystem at all, devlabel will then fall back on using SCSI
> UUIDs or IDE identifiers as it used before (these support disk-wide
> failures, when /dev/sdb6 becomes /dev/sda6).
>
> As well, devlabel now also supports automounting. For example, with a USB
> flash reader, you should now add it to devlabel with the --automount option.
> If --automount is specified, every time you hotplug your device, it will
> check /etc/fstab for an entry containing the symlink that you've added for
> this device, and if it finds one, it will automatically mount it. Nice and
> simple.
>
> Lastly, you can also now do adds by UUID. This is especially helpful in
> shared storage environments. For example, you can add a symlink on the
> master node and then add by UUID on all the secondary nodes to ensure that
> the same symlink on all nodes points to the same shared storage device
> regardless of the device naming scheme of those nodes.
>
> Gary Lerhaupt
> Linux Development
> Dell Computer Corporation
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
--
Jeremy Jackson <[email protected]>

2003-01-20 17:53:29

by Lerhaupt, Gary

[permalink] [raw]
Subject: RE: Devlabel: static device naming via symlinks (improved)

An interesting point. Though, if two devices have the exact same UUID,
devlabel refuses to add a symlink to either one of them. I will set up LVM
on a box around here and confirm this.

Gary

-----Original Message-----
From: Jeremy Jackson [mailto:[email protected]]
Sent: Saturday, January 18, 2003 10:48 AM
To: [email protected]
Cc: [email protected]
Subject: Re: Devlabel: static device naming via symlinks (improved)


I've been using EVMS (http://evms.sourceforge.net and it's snapshot
capability (as well as LVM's I assume) can create "partitions" or
volumes with duplicate fs UUIDs. Perhaps someone using EVMS may not use
devlabel since it includes that functionality, but in the LVM case you
may want to investigate the effect of duplicate UUIDs.

Regards,

Jeremy

On Fri, 2003-01-17 at 17:15, [email protected] wrote:
> I've added a couple useful features to devlabel (available at
> http://domsch.com/linux/devlabel). Of the foremost of these is that it
now
> includes the usage of Partition UUIDs (as provided by ext2, ext3, xfs, jfs
> or ocfs). Since these UUIDs are partition specific, if a partition-level
> failure event occurs (eg. you delete /dev/sde6 and /dev/sde7 then becomes
> /dev/sde6), devlabel is now smart enough to handle it for the
aforementioned
> filesystem types. If you aren't using one of these filesystem types or if
> there is no filesystem at all, devlabel will then fall back on using SCSI
> UUIDs or IDE identifiers as it used before (these support disk-wide
> failures, when /dev/sdb6 becomes /dev/sda6).
>
> As well, devlabel now also supports automounting. For example, with a USB
> flash reader, you should now add it to devlabel with the --automount
option.
> If --automount is specified, every time you hotplug your device, it will
> check /etc/fstab for an entry containing the symlink that you've added for
> this device, and if it finds one, it will automatically mount it. Nice
and
> simple.
>
> Lastly, you can also now do adds by UUID. This is especially helpful in
> shared storage environments. For example, you can add a symlink on the
> master node and then add by UUID on all the secondary nodes to ensure that
> the same symlink on all nodes points to the same shared storage device
> regardless of the device naming scheme of those nodes.
>
> Gary Lerhaupt
> Linux Development
> Dell Computer Corporation
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
--
Jeremy Jackson <[email protected]>