Solaris

Oh no, please don't have a swap file in /var/tmp/ !! "Application is slow, perhaps it helps to delete some temporary files..."
Better something like /critical_swapfile/
And then, isn't a sparse file a risk by itself? What happens if there is no free disk space in the file system? Kernel panic?

Well, nothing particular will happen if that file is removed by a clueless administrator. The lofi device will still point to the same inode, now linkless. After a reboot, the system will start without that extra swap configured whether the file is removed or not.
I'm not sure but it might lock or panic indeed. To clarify, my suggestion actually assumes no physical swapping will occur, and is just there to trick an application that demand plenty of swap but won't write anything to it. As you might know, Solaris is not overcommiting memory so each reservation must be backed by some storage (RAM or swap) but there is no physical I/O as long as that reserved memory is not accessed.

Hi jilliare,

Thanks for your reply.
Reason for not using a swapfile is mostly due to standardization. We have a few solaris servers running and none of them are using swapfile.

The 100GB partition is totally empty, except that I have newfs it. Probably touch some files in it, but I have rm -r *.

Thus i am thinking of using it to replace my current 32GB swap partition.
The only concern I have is (-- the UFS filesystem on it ) and if there will be any problem if the OS actually start utilizing the swap space.

Regards,
Noob

Well, if your 100Gb partition is empty, you can either create a swapfile in it, or trash the filesystem on it and use the partition as swap. The former method (swapfile) would be simpler to implement.

You should never configure a partition containing a file system as a raw swap device, especially if it is mounted at the same time. In any case, any actual paging operation will corrupt the file system.

Hi MadeInGermany,

Yeap. I am using SPARC and i managed to add the UFS partition as swap. It did not prompt me any error (but i am not sure if it is because the swap is not used yet)

I have also change the partition flag from wm to wu.

Regards,
Noob

---------- Post updated at 06:50 AM ---------- Previous update was at 06:47 AM ----------

Hi Jilliagre,

Thanks. Sorry for my poor english, but what do you mean by "trash the filesystem on it" ?
Do you mean to mount the 100GB partition as swap and ignore the fact of the UFS filesystem on it ?
(p.s. the 100GB is already umounted from its original mountpoint)

Regards,
Noob

You do not need to manually trash anything. Swap does not care about any pre-existing data.

Hi MadeinGermany,

Thanks for your reply. Seeing the word trash make me curious.
How do you trash a filesystem ? What do you guys mean by trash ?

Regards,
Noob