tmpfs and ufs/zfs are different things.
You limit the amount of "swap" (i.e. disk-backed 'memory') by varying
the size of the device added using "swap -a", or the lines in vfstab
with 'swap' in the "FS type" column. This is the "memory" available to
all processes.
You limit the amount of swap use by tmpfs by using the "size=" mount
option or the options column of the /tmp line in vfstab (which has an FS
type of tmpfs, not swap).
Whilst I can't demonstrate re-mounting /tmp with the size= option, I can
mount a new filesystem from swap in the same way whilst using zfs root:
# mount -Ftmpfs swap /a
# df -h /a
Filesystem Size Used Avail Use% Mounted on
swap 704M 0 704M 0% /a
# umount /a
# mount -Ftmpfs -osize=100m swap /a
# df -h /a
Filesystem Size Used Avail Use% Mounted on
swap 100M 0 100M 0% /a
See mount_tmpfs(1M) for the full range of options for tmpfs mounting.
These options are independent of your root filesystem type.
If you're saying that with zfs root, setting "size=" on the tmpfs line
of /etc/vfstab does not work, I would say a bug needs to be logged about it.
Regards,
Brian
On 02/ 1/10 06:15 AM, Prakash Kochummen wrote:
Hi,
While using ufs root, we had an option for limiting the /tmp size using mount
-o size manual option or setting size=1024m in the vfstab.
Do we have any comparable option available when we use zfs root. If we execute
zfs set size=1024m rpool/swap
it resizes the whole of the swap area which results in reducing the VM size.
AFAIK in the ufs option for limiting swap size, we are just limiting the
filesystem behaviour of the tmpfs filesystem while the kernel will still be
able to use the swap space for paging etc. Is this correct understanding.
Thanks in advance.
Rgds
PK
--
Brian Ruthven
Solaris Revenue Product Engineering
Sun Microsystems UK
Sparc House, Guillemont Park, Camberley, GU17 9QG
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