[CentOS] LVM Input/output error
William L. Maltby
BillsCentOS at triad.rr.com
Mon Jul 10 15:13:42 UTC 2006
On Mon, 2006-07-10 at 17:09 +0300, itayf at nospammail.net wrote:
> > > [root at frodo ~]# sfdisk -l /dev/sdc
> > >
> > ><snip>
> Had to wait until I came back to work and could reboot the
> machine. Using William's instructions, modulus using 8e as Matt
> Hyclak pointed out, seems to solve the problem. Everything seems
> to work fine: lvcreation, writing files, etc.
>
> The only odd thing is in regard to the output of sfdisk. Note
> the warning when 'sfdisk -l' is invoked without a device
> argument. According to the man page this is a legitimate call
> that should produce output similar in nature to 'fdisk -l' (which
> works as expected).
>
> <man>
> The second type of invocation: sfdisk -l [options] device will list
> the partitions on this device. If the device argument is omitted, the
> partitions on all hard disks are listed.
> % sfdisk -l /dev/hdc
> </man>
>
> I am quite sure that this is an 'sfdisk' issue unrelated to the
> problem I needed to solve. But I would like to be careful before
> I declare [RESOLVED].
My workstation, in use for over a year now, shows the same warning
message (start=63...) as your transcript. Further, having used sfdisk
for a *long* time for some fairly rigorous applications, I have complete
confidence in it. Reread the man sections on the "+" and "-" suffix and
you get your first clue. The run sfdisk again and add "-uS" and I think
you will be OK with it.
It will also give warning messages if the true geometry of a drive
appears to be other than what is shown in the disk label (often called
MBR).
Although I have faith in the software, the doc (as is normal?) is not so
trustworthy. You'll see only 1 HD in my transcript at the end of this
reply, but look at this.
[root at wlmlfs08 ~]# sfdisk -l -uS /dev/hdd
Disk /dev/hdd: 7297 cylinders, 255 heads, 63 sectors/track
Units = sectors of 512 bytes, counting from 0
Device Boot Start End #sectors Id System
/dev/hdd1 * 63 208844 208782 83 Linux
/dev/hdd2 208845 117226304 117017460 8e Linux LVM
/dev/hdd3 0 - 0 0 Empty
/dev/hdd4 0 - 0 0 Empty
There is a conflict in the man page: the prototype shows device is not
optional if options are provided but the paragraph you high-lighted says
it has a behavior that makes it optional. On my machine, the missing
device specification does not produce the documented behavior. I
conclude that if options are given, device is not optional *unless* you
accept undefined behavior as acceptable! =>:-O
>
> Perhaps I will try sfdisk with a different machine to see if
> there is a difference.
I don't think you'll see any difference if the config is similar. I've
attached my transcript below.
>
> Thanks,
> Itay
> <snip>
=============================================================
[root at wlmlfs08 ~]# sfdisk -l
Disk /dev/hda: 12161 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from
0
Device Boot Start End #cyls #blocks Id System
/dev/hda1 * 0+ 12 13- 104391 83 Linux
/dev/hda2 13 2445 2433 19543072+ 8e Linux LVM
/dev/hda3 2446 4876 2431 19527007+ 8e Linux LVM
/dev/hda4 0 - 0 0 0 Empty
Warning: start=63 - this looks like a partition rather than
the entire disk. Using fdisk on it is probably meaningless.
[Use the --force option if you really want this]
[root at wlmlfs08 ~]# sfdisk -l -uS
Disk /dev/hda: 12161 cylinders, 255 heads, 63 sectors/track
Units = sectors of 512 bytes, counting from 0
Device Boot Start End #sectors Id System
/dev/hda1 * 63 208844 208782 83 Linux
/dev/hda2 208845 39294989 39086145 8e Linux LVM
/dev/hda3 39294990 78349004 39054015 8e Linux LVM
/dev/hda4 0 - 0 0 Empty
Warning: start=63 - this looks like a partition rather than
the entire disk. Using fdisk on it is probably meaningless.
[Use the --force option if you really want this]
[root at wlmlfs08 ~]#
============================================================================
--
Bill
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