swap partition missing?

[Hongwei Li]

> Hongwei Li wrote:

>>
>> Yes, it works.  Thank you very much!  Now, I have questions:
>>
>> 1. What's the use of mkswap -L SWAP-hda7 /dev/hda7? I don't see any
>> effect?
>
> It *should* be setting the "filesystem label" of the partition to
> "SWAP-hda7" so that mkswap can find it by name rather than being needed
> to be told where exactly the swap partition is.
>
>> 2. When I put the original entry back to /etc/fstab as:
>> LABEL=SWAP-hda7         swap     swap    defaults 0 0
>>
>> it does not work again.  I have to put /dev/hda7 in it.  How to let the
>> original entry work -- the above mkswap ... does not have effect?
>
> Was your system swapping to that partition at the time you did the mkswap?
>
>  > Why do we need those LABEL=... in fstab?
>
> The idea is that labels should be less of a moving target than device
> names. For example, lots of people found that their SATA drives moved
> from being /dev/hdX to /dev/sdX fairly recently. Labelling filesystems
> means that the OS can find them no matter what the device name is. This
> isn't without its problems (e.g. when moving disks between machines,
> resulting in multiple partitions with the same labels), but that's why
> they're there.
>
> Labels for swap partitions are discussed at:
> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=127892
>
> Paul.
>
> --

Here is what I did in the order:

# swapoff -a

# mkswap -L SWAP-hda7 /dev/hda7
Setting up swapspace version 1, size = 2097410 kB

# vi /etc/fstab
(set:
LABEL=SWAP-hda7         swap     swap    defaults        0 0
)

# swapon -a
swapon: cannot find the device for LABEL=SWAP-hda7

# vi /etc/fstab
(set:
/dev/hda7         swap        swap    defaults        0 0
)

# swapon -a

# free
             total       used       free     shared    buffers     cached
Mem:       1035748     216116     819632          0      13096     119504
-/+ buffers/cache:      83516     952232
Swap:      2048248          0    2048248

Should I do it differently?

Thanks!

Hongwei