Can one now help?
Christofer C. Bell
christofer.c.bell at gmail.com
Sun Jul 18 21:56:35 UTC 2010
On 7/18/10, Parshwa Murdia <b330bkn at gmail.com> wrote:
> one things is that when you say sdXN, X is the drive letter means what
> drive letter is give to the linux partition? in windows if i see, its H so
> it should be like sdH9?? in the line:
>
> mount /dev/sdXN /mydisk
>
> but the error i get is:
> *
> mount: you must specify the filesystem type* (which comes in the terminal)
>
The X there isn't really a drive letter. Under Windows, a "drive letter"
really refers to a partition, not a disk, and so the N (the number) is more
analogous to a drive letter (but not really, keep reading!). The X refers
to the disk itself. Under Linux, the 4 portions of that device name are:
* Controller type (IDE, SCSI, SATA, etc) (SCSI and SATA both use 's', IDE
uses 'h')
* Device type (disk, tape, etc) (d for disk, t for tape, etc)
* Disk/Controller position (where is the disk on the controller? Or which
controller? Enumerated starting with a, sda, sdb, sdc, etc)
* Partition number (enumerated starting with 1, then 2, 3, 4, etc)
Under this scheme, the first partition of your first disk will be sda1.
Let's look at this:
s - controller is SATA
d - we're talking about a disk device
a - we're talking about the first disk on the controller, really with SATA
we're talking about the first controller)
1 - we're talking referencing the first partition on that disk
On Intel PC systems (what most people run Fedora on), the "partition number"
field can also tell you what kind of partition it is. Partitions 1 through
4 are *always* Primary partitions. Partition 5 is *always* an Extended
partition. Extended partitions will never have a filesystem written
directly to them. Instead, they will contain Logical partitions. These
will be all partitions numbered 6 and beyond.
Let's take a look at the disks in my own system here. This machine contains
3 disks, each 1.5 TB in size. I've deleted all the confusing RAID stuff and
partition statistics since we don't care about that here:
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 182402 1464625152 8e Linux LVM
Device Boot Start End Blocks Id System
/dev/sdb1 1 182401 1465136032 fd Linux raid
autodetect
Device Boot Start End Blocks Id System
/dev/sdc1 1 182401 1465136001 fd Linux raid
autodetect
We can see from this output that the system has 3 SATA controllers that are
in use. This is evident by each disk being enumerated as sda, sdb, and
sdc. Remember, s = SCSI or SATA (SATA here), the physical disk devices are
a, b, and c. There are 2 partitions (1 and 2) on the first disk, then 1
partition each on the other 2 disks.
Now, all of this ignores what's likely the case if you installed Fedora 13
with the installation defaults. In that case, you're likely using LVM (and
none of the information folks have given so far is going to work). Notice
that in the example above, disk sda2 is of type "Linux LVM" -- this means
it's being used as a PV (physical volume) under LVM management. We can use
the command 'pvscan' to get a listing of all PVs (again, physical volumes,
ie; real disk partitions) that are being used and what VG (volume group)
they contain:
lvm> pvscan
PV /dev/sda2 VG vg_circe lvm2 [1.36 TiB / 0 free]
PV /dev/md0 VG homevg_1 lvm2 [1.36 TiB / 0 free]
Total: 2 [2.73 TiB] / in use: 2 [2.73 TiB] / in no VG: 0 [0 ]
lvm>
And here it is! We see that PV /dev/sda2 (the second partition of the disk
on the first SATA controller) contains VG (again, volume group, sort of like
an extended partition) vg_circe. Now, what is inside that volume group? We
can use the command lvscan to find out:
lvm> lvscan
ACTIVE '/dev/homevg_1/homelv_1' [1.36 TiB] inherit
ACTIVE '/dev/vg_circe/lv_root' [1.36 TiB] inherit
ACTIVE '/dev/vg_circe/lv_swap' [5.44 GiB] inherit
lvm>
And there is our root partition. It's /dev/vg_circe/lv_root.
Now, looking at what you've provided, here's the output of fdisk -l for your
machine:
Device Boot Start End Blocks Id System
/dev/sda1 1 5737 46082421 7 HPFS/NTFS
/dev/sda2 5738 30400 198105547+ f W95 Ext'd (LBA)
/dev/sda5 5738 9561 30716248+ 7 HPFS/NTFS
/dev/sda6 9562 13385 30716248+ 7 HPFS/NTFS
/dev/sda7 13386 15935 20482843+ 7 HPFS/NTFS
/dev/sda8 * 15936 15961 204799+ 83 Linux
/dev/sda9 15961 28596 101487615+ 8e Linux LVM
You mentioned you were confused that you didn't see sda3 or sda4. If you
recall what I said earlier, this is normal. That's because you only have 2
primary partitions on your disk. You have an extended partition (always 5)
that contains 4 logical partitions (6, 7, 8, and 9). Since you only have 2
primary partitions, you won't have an entry for 3 or 4, just 1 and 2.
In looking at your list here, it's likely that sda8 is your /boot filesystem
and that sd9 contains your root filesystem and swap partition (assuming a
default selection of settings during the installation of Fedora). Because
LVM is in use here, we can't mount the disk partitions directly. Remember,
the disk partition is an LVM physical volume, it's not a filesystem that can
be mounted. However, the logical volumes *are* normal filesystems that can
be mounted.
I can't see the hostname of your machine, but I'll wager you didn't change
the default installation name of vg_$(hostname) so I'll go with that here:
# mount -t ext4 /dev/mapper/vg_$(hostname)/lv_root /mnt
This will mount the logical volume "lv_root" contained in volume group
"vg_yourhostname" under /mnt with a filesystem type of ext4 (what your
system is most likely using). If you receive an error about the wrong
filesystem type, then you may be using the ext3 filesystem. In that case,
simply replace ext4 with ext3. You can then follow the rest of the
information provided to restore your backup copy of the fstab (you'll
restore your backup to /mnt/etc/fstab, remember, you've mounted your
system's root partition under /mnt, the actual /etc directory when booted
off the Live CD is the /etc/ on the Live CD).
Here's a real example, done on my own machine using the Live CD:
[liveuser at localhost ~]$ su -
[root at localhost ~]# lvscan
ACTIVE '/dev/homevg_1/homelv_1' [1.36 TiB] inherit
ACTIVE '/dev/vg_circe/lv_root' [1.36 TiB] inherit
ACTIVE '/dev/vg_circe/lv_swap' [5.44 GiB] inherit
[root at localhost ~]# mount -t ext4 /dev/mapper/vg_circe-lv_root /mnt
[root at localhost ~]# ls -l /mnt/etc/fstab*
-rw-r--r--. 1 root root 957 Jun 27 05:00 /mnt/etc/fstab
-rw-r--r--. 1 root root 861 Jun 26 17:46 /mnt/etc/fstab.20100626
[root at localhost ~]#
There's only one part where this gets confusing. The lvscan told us that
the logical volume is /dev/vg_circe/lv_root. But when we mount it, we use
/dev/mapper/vg_circe-lv_root. Note how we've included "mapper" and we've
changed a forward slash (/) to a dash (-). All you need to do to fix this
is copy your backup fstab to /mnt/etc/fstab and reboot.
Good luck!
--
Chris
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