[CentOS] LVM Input/output error

Mon Jul 10 15:32:21 UTC 2006
William L. Maltby <BillsCentOS at triad.rr.com>

On Mon, 2006-07-10 at 17:09 +0300, itayf at nospammail.net wrote:
> > > [root at frodo ~]# sfdisk -l /dev/sdc
> > ><snip>

> Disk /dev/sda: 30401 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/sda1   *      0+     12      13-    104391   83  Linux
> /dev/sda2         13   30400   30388  244091610   8e  Linux LVM
> /dev/sda3          0       -       0          0    0  Empty
> /dev/sda4          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]
> <snip>

BTW: I wanted to mention for folks that may not know. If your disk is
not to be booted, you can *choose* to not partition it, with little
concern. Further, even bootable HDs need not be partitioned.

Since a "cylinder" (in the typical LBA world) is 8MB, you may want to
gain that 8MB, if you are really tight about things. You can avoid
partitioning altogether or you can start your first partition right
after the disk label (MBR) or on the track following. Long ago and far
away, this used to have performance implications. No more.

But be careful and know what else you are using that may affect you.
Some MS stuff uses extra blocks; I also hear that some HD-related
software uses "assumed" free space in the first cylinder, etc.

But if you do just Linux, you *can* skip the partitions. Even with LVM.
Or start right after the MBR (disk label).

Be sure you consider various fall-back processes for "less than
disaster" recovery. Partitions might still be useful on one or more of
your HDs to have backup boot partitions, finer-grained LVM PV
allocations, etc.

As with writing ext2 instead of ISO file systems to CD, it can be useful
but be sure you don't thoughtlessly give up useful compatibility or

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