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Old 08-17-2008, 12:25 PM
Jay Ridgley
 
Default UUID question

Folks,

I have two partitions that have UUIDs assigned that were assigned during
the upgrade to edgy, /dev/sda1 and /dev/sda5, the first is mounted as /
and the second one as swap. The names have changed due to the SCSI
controller being assigned /dev/sda since sudo fdisk -l shows them as
/dev/sdb1 and /dev/sdb5.

I also have three others that do not, /dev/hdd, /dev/sdc1 and
/dev/sdc2, these are mounted as /media/cdrom, /home and /archive
respectively.

It appears that my scsi cdrom /dev/scd1 is not included in /etc/fstab,
however, the other cdrom is included as /dev/hdd with a mount point of
/media/cdrom0.

My question is are the UUIDs required or can I change them back to the
"old fashioned" names (/dev/sdb1 and /dev/sdb5) that I have used for
years with Linux and various other UNIX systems? Can I safely create an
entry in /etc/fstab for the SCSI CDROM?

Cheers,
Jay

--


Jay Ridgley
jridgley2@austin.rr.com
Registered Linux User ID - 9115
Registered Ubuntu User ID - 23320


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Old 08-17-2008, 01:07 PM
Nils Kassube
 
Default UUID question

Jay Ridgley wrote:
> I have two partitions that have UUIDs assigned that were assigned
> during the upgrade to edgy, /dev/sda1 and /dev/sda5, the first is
> mounted as / and the second one as swap. The names have changed due to
> the SCSI controller being assigned /dev/sda since sudo fdisk -l shows
> them as /dev/sdb1 and /dev/sdb5.

The SCSI controller is definitely not assigned a device name, only the
disks connected to the controller will get device names. However I can't
tell you why you don't have /dev/sda* entries.

> I also have three others that do not, /dev/hdd, /dev/sdc1 and
> /dev/sdc2, these are mounted as /media/cdrom, /home and /archive
> respectively.
>
> It appears that my scsi cdrom /dev/scd1 is not included in /etc/fstab,
> however, the other cdrom is included as /dev/hdd with a mount point of
> /media/cdrom0.
>
> My question is are the UUIDs required or can I change them back to the
> "old fashioned" names (/dev/sdb1 and /dev/sdb5) that I have used for
> years with Linux and various other UNIX systems?

Well, you _can_ change the entries to device names and it will work, if
the device names are _always_ the device names you have now. But as you
mentioned in your first paragraph, you can't be sure that the disk which
is now at sdb is always sdb - it has been sda before. At least that's how
I understand it. Now, if device names change, after you have renamed the
fstab entries to device names, your system won't work any longer. May I
ask why you want to use device names in your fstab?

> Can I safely create
> an entry in /etc/fstab for the SCSI CDROM?

Sure.


Nils

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Old 08-17-2008, 03:17 PM
Derek Broughton
 
Default UUID question

Jay Ridgley wrote:

> I have two partitions that have UUIDs assigned that were assigned during
> the upgrade to edgy, /dev/sda1 and /dev/sda5, the first is mounted as /
> and the second one as swap. The names have changed due to the SCSI
> controller being assigned /dev/sda since sudo fdisk -l shows them as
> /dev/sdb1 and /dev/sdb5.
...
> My question is are the UUIDs required or can I change them back to the
> "old fashioned" names (/dev/sdb1 and /dev/sdb5) that I have used for
> years with Linux and various other UNIX systems? Can I safely create an
> entry in /etc/fstab for the SCSI CDROM?

Here we go again...

Of course you can change back to old fashioned names - but why would you
expect this to continue to work? Your devices have changed names before,
and they'll likely change again. You're _much_ safer to use the UUIDs.
And sure you can create an entry for the SCSI CD.
--
derek


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Old 08-17-2008, 10:28 PM
Jay Ridgley
 
Default UUID question

Nils wrote:

Date: Sun, 17 Aug 2008 15:07:22 +0200 From: Nils Kassube
<kassube@gmx.net> Subject: Re: UUID question To:
ubuntu-users@lists.ubuntu.com Message-ID:
<200808171507.22272.kassube@gmx.net> Content-Type: text/plain;
charset="iso-8859-1" Jay Ridgley wrote:

> > I have two partitions that have UUIDs assigned that were assigned
> > during the upgrade to edgy, /dev/sda1 and /dev/sda5, the first is
> > mounted as / and the second one as swap. The names have changed due to
> > the SCSI controller being assigned /dev/sda since sudo fdisk -l shows
> > them as /dev/sdb1 and /dev/sdb5.
>

The SCSI controller is definitely not assigned a device name, only the
disks connected to the controller will get device names. However I can't
tell you why you don't have /dev/sda* entries.

--> My comment
--> It was used for my HP Photosmart C3180 All-in-ONE... see below

> > I also have three others that do not, /dev/hdd, /dev/sdc1 and
> > /dev/sdc2, these are mounted as /media/cdrom, /home and /archive
> > respectively.
> >
> > It appears that my scsi cdrom /dev/scd1 is not included in /etc/fstab,
> > however, the other cdrom is included as /dev/hdd with a mount point of
> > /media/cdrom0.
> >
> > My question is are the UUIDs required or can I change them back to the
> > "old fashioned" names (/dev/sdb1 and /dev/sdb5) that I have used for
> > years with Linux and various other UNIX systems?
>

Well, you _can_ change the entries to device names and it will work, if
the device names are _always_ the device names you have now. But as you
mentioned in your first paragraph, you can't be sure that the disk which
is now at sdb is always sdb - it has been sda before. At least that's how
I understand it. Now, if device names change, after you have renamed the
fstab entries to device names, your system won't work any longer. May I
ask why you want to use device names in your fstab?

--> My comment:

--> I am just more used to that notation, however, after some more research I think I need to learn the new method... see below

> > Can I safely create
> > an entry in /etc/fstab for the SCSI CDROM?
>

Sure.

--> My comment:

--> I think I need to use a UUID here also...

Nils

Derek ALSO wrote:

--snip my OP--

Here we go again...

Of course you can change back to old fashioned names - but why would you
expect this to continue to work? Your devices have changed names before,
and they'll likely change again. You're _much_ safer to use the UUIDs.
And sure you can create an entry for the SCSI CD.

-- derek

--> My comment:

--> I was not aware of device names changing during installation, however, as you both may see below they do..

--> Additional info below ---


jay@polar:~$ lsscsi
[0:0:0:0] disk SEAGATE ST318404LW 0006 /dev/sdb
[0:0:1:0] disk SEAGATE ST318404LW 0006 /dev/sdc
[0:0:4:0] tape Seagate STT20000N 6A51 /dev/st0
[0:0:5:0] cd/dvd YAMAHA CRW8824S 1.00 /dev/scd0
[3:0:1:0] cd/dvd SAMSUNG CD-ROM SC-148C B100 /dev/scd1
[4:0:0:0] disk HP Photosmart C3180 1.00 /dev/sda

jay@polar:~$ lsusb
Bus 002 Device 001: ID 0000:0000
Bus 001 Device 004: ID 03f0:5611 Hewlett-Packard PhotoSmart C3180
Bus 001 Device 003: ID 058f:6254 Alcor Micro Corp.
Bus 001 Device 001: ID 0000:0000

jay@polar:~$ cat /etc/fstab
# /etc/fstab: static file system information.
#
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc defaults 0 0
# /dev/sda1 -- converted during upgrade to edgy
UUID=aa505a5b-90e4-4f99-94d3-3adc17db5e41 / ext3 defaults,errors=remount-ro 0 1
# /dev/sda5 -- converted during upgrade to edgy
UUID=abe9cd12-9e62-4c8a-beb3-d1e022ba02f9 none swap sw 0 0
/dev/hdd /media/cdrom0 udf,iso9660 user,noauto 0 0
# next lines added by CDJ Systems - 06/28/08
/dev/sdc2 /home ext3 rw 0 2
/dev/sdc1 /archive ext3 rw,noauto 0 2

There are some interesting things in the above information:

1. The /dev/sda device is really my printer that is connected via USB and I would to hazard a guess refers to the scanner.
Why is it identified as a SCSI disk?

2. The SAMSUNG CDROM is NOT a SCSI device but is connected via the IDE bus.

3. The device /dev/hdd does not exist (ls -l /dev/hdd shows that) and I would assume a mount command would also fail.

The question now becomes how do I go about generating UUIDs for these other devices (those without them) and get those identifiers properly assigned?

Sorry for the length of this but want to avoid problems down the road...

Cheers,
Jay

--


Jay Ridgley
jridgley2@austin.rr.com
Registered Linux User ID - 9115
Registered Ubuntu User ID - 23320


--
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Old 08-18-2008, 04:44 AM
Derek Broughton
 
Default UUID question

Jay Ridgley wrote:

> Nils wrote:
>
> Date: Sun, 17 Aug 2008 15:07:22 +0200 From: Nils Kassube
> <kassube@gmx.net> Subject: Re: UUID question To:
> ubuntu-users@lists.ubuntu.com Message-ID:
> <200808171507.22272.kassube@gmx.net> Content-Type: text/plain;
> charset="iso-8859-1" Jay Ridgley wrote:
>
>> > I have two partitions that have UUIDs assigned that were assigned
>> > during the upgrade to edgy, /dev/sda1 and /dev/sda5, the first is
>> > mounted as / and the second one as swap. The names have changed due to
>> > the SCSI controller being assigned /dev/sda since sudo fdisk -l shows
>> > them as /dev/sdb1 and /dev/sdb5.
>>
>
> The SCSI controller is definitely not assigned a device name, only the
> disks connected to the controller will get device names. However I can't
> tell you why you don't have /dev/sda* entries.
>
> --> My comment
> --> It was used for my HP Photosmart C3180 All-in-ONE... see below
>
>> > I also have three others that do not, /dev/hdd, /dev/sdc1 and
>> > /dev/sdc2, these are mounted as /media/cdrom, /home and /archive
>> > respectively.
>> >
>> > It appears that my scsi cdrom /dev/scd1 is not included in /etc/fstab,
>> > however, the other cdrom is included as /dev/hdd with a mount point of
>> > /media/cdrom0.
>> >
>> > My question is are the UUIDs required or can I change them back to the
>> > "old fashioned" names (/dev/sdb1 and /dev/sdb5) that I have used for
>> > years with Linux and various other UNIX systems?
>>
>
> Well, you _can_ change the entries to device names and it will work, if
> the device names are _always_ the device names you have now. But as you
> mentioned in your first paragraph, you can't be sure that the disk which
> is now at sdb is always sdb - it has been sda before. At least that's how
> I understand it. Now, if device names change, after you have renamed the
> fstab entries to device names, your system won't work any longer. May I
> ask why you want to use device names in your fstab?
>
> --> My comment:
>
> --> I am just more used to that notation, however, after some more
> research I think I need to learn the new method... see below
>
>> > Can I safely create
>> > an entry in /etc/fstab for the SCSI CDROM?
>>
>
> Sure.
>
> --> My comment:
>
> --> I think I need to use a UUID here also...
>
> Nils
>
> Derek ALSO wrote:
>
> --snip my OP--
>
> Here we go again...
>
> Of course you can change back to old fashioned names - but why would you
> expect this to continue to work? Your devices have changed names before,
> and they'll likely change again. You're _much_ safer to use the UUIDs.
> And sure you can create an entry for the SCSI CD.
>
> -- derek
>
> --> My comment:
>
> --> I was not aware of device names changing during installation,
> however, as you both may see below they do..
>
> --> Additional info below ---
>
>
> jay@polar:~$ lsscsi
> [0:0:0:0] disk SEAGATE ST318404LW 0006 /dev/sdb
> [0:0:1:0] disk SEAGATE ST318404LW 0006 /dev/sdc
> [0:0:4:0] tape Seagate STT20000N 6A51 /dev/st0
> [0:0:5:0] cd/dvd YAMAHA CRW8824S 1.00 /dev/scd0
> [3:0:1:0] cd/dvd SAMSUNG CD-ROM SC-148C B100 /dev/scd1
> [4:0:0:0] disk HP Photosmart C3180 1.00 /dev/sda
>
> jay@polar:~$ lsusb
> Bus 002 Device 001: ID 0000:0000
> Bus 001 Device 004: ID 03f0:5611 Hewlett-Packard PhotoSmart C3180
> Bus 001 Device 003: ID 058f:6254 Alcor Micro Corp.
> Bus 001 Device 001: ID 0000:0000
>
> jay@polar:~$ cat /etc/fstab
> # /etc/fstab: static file system information.
> #
> # <file system> <mount point> <type> <options> <dump> <pass>
> proc /proc proc defaults 0 0
> # /dev/sda1 -- converted during upgrade to edgy
> UUID=aa505a5b-90e4-4f99-94d3-3adc17db5e41 / ext3
> defaults,errors=remount-ro 0 1
> # /dev/sda5 -- converted during upgrade to edgy
> UUID=abe9cd12-9e62-4c8a-beb3-d1e022ba02f9 none swap sw 0 0
> /dev/hdd /media/cdrom0 udf,iso9660 user,noauto 0 0
> # next lines added by CDJ Systems - 06/28/08
> /dev/sdc2 /home ext3 rw 0 2
> /dev/sdc1 /archive ext3 rw,noauto 0 2
>
> There are some interesting things in the above information:
>
> 1. The /dev/sda device is really my printer that is connected via USB and
> I would to hazard a guess refers to the scanner.
> Why is it identified as a SCSI disk?
>
> 2. The SAMSUNG CDROM is NOT a SCSI device but is connected via the IDE
> bus.

It should probably be on /dev/scd0

> 3. The device /dev/hdd does not exist (ls -l /dev/hdd shows that) and I
> would assume a mount command would also fail.
>
> The question now becomes how do I go about generating UUIDs for these
> other devices (those without them) and get those identifiers properly
> assigned?

Devices don't have UUIDs, filesystems do. "sudo blkid" should tell you what
the UUID of every currently mounted filesystem is. Using a UUID for your
CDROM would be kind of pointless, though - as every CD would have a
different UUID.
--
derek


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Old 08-18-2008, 05:43 AM
Nils Kassube
 
Default UUID question

Jay Ridgley wrote:
> --> I was not aware of device names changing during installation,
> however, as you both may see below they do..
>
> jay@polar:~$ lsscsi
> [0:0:0:0] disk SEAGATE ST318404LW 0006 /dev/sdb
> [0:0:1:0] disk SEAGATE ST318404LW 0006 /dev/sdc
> [0:0:4:0] tape Seagate STT20000N 6A51 /dev/st0
> [0:0:5:0] cd/dvd YAMAHA CRW8824S 1.00 /dev/scd0
> [3:0:1:0] cd/dvd SAMSUNG CD-ROM SC-148C B100 /dev/scd1
> [4:0:0:0] disk HP Photosmart C3180 1.00 /dev/sda
>
> jay@polar:~$ lsusb
> Bus 002 Device 001: ID 0000:0000
> Bus 001 Device 004: ID 03f0:5611 Hewlett-Packard PhotoSmart C3180
> Bus 001 Device 003: ID 058f:6254 Alcor Micro Corp.
> Bus 001 Device 001: ID 0000:0000
>
> There are some interesting things in the above information:
>
> 1. The /dev/sda device is really my printer that is connected via USB
> and I would to hazard a guess refers to the scanner. Why is it
> identified as a SCSI disk?

It isn't identified as a SCSI disk, but as a disk. The kernel doesn't
distinguish any more between SCSI, IDE, USB, whatever type of disk when
it comes to device names. So your HP Photosmart C3180 is identified as a
disk which really is connected via USB.

And here we see the cause of disk renaming. The C3180 is now sda. If you
remove it while you boot the machine, your disk which is now sdb would
become sda, the disk which is now sdc would become sdb, and if you later
connect the C3180 again, it will become sdc. It all depends on the
sequence in which the devices are found by the kernel.

> 2. The SAMSUNG CDROM is NOT a SCSI device but is connected via the IDE
> bus.

Yes, same thing. Any CD/DVD drive gets a device name /dev/scd* nowadays,
no matter how it is connected.

> 3. The device /dev/hdd does not exist (ls -l /dev/hdd shows that) and I
> would assume a mount command would also fail.

Right. You would need an entry for /dev/scd0 and /dev/scd1 instead. OTOH
you don't really need an entry for the CD/DVD device. If you insert a
disk, it usually gets mounted automatically (or you are asked if you want
to mount it), even if there is no entry in /etc/fstab. But you probably
know that already, because there is no such entry in your fstab.

> The question now becomes how do I go about generating UUIDs for these
> other devices (those without them) and get those identifiers properly
> assigned?

Your ext3 partitions already have a UUID. You can see it with the command

sudo blkid /dev/sdc1 /dev/sdc2

For the CD/DVD devices you can't use UUIDs. The UUID is used to identify a
file system, not a disk device. Now, every CD / DVD you put in the drive
would need its own UUID, but I don't know if that is supported at all by
the ISO9660 / UDF file system standard which is used for CDs / DVDs.


Nils

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