Hi All,
a couple of days ago, I once again ran into the issues regarding
layered mounts of diffrent filesystems and lofs mounts depending upon
other mounts. Two more or less recent pointers:
http://bugs.opensolaris.org/view_bug.do?bug_id=6464201
http://www.opensolaris.org/jive/thread.jspa?messageID=122908
>From my experience, the most important issues are that currently there
is no generic way to
- mount filesystems on a metaset (can fail if metaset auto-take does
not work or not supported as in Sun Cluster)
-> we need a metaset take import method and a filesystem mount
method which depends upon the metaset
- mount filesystems which depend upon each other but are of different
FSTypes like NFS, ZFS, UFS or lofs. The classic is that a lofs mount
of an NFS mount or even an UFS mount fails (in some cases), if
simply being added to the vfstab.
There are two different kinds of dependencies, but both boil down to
a dependency from one mount to another where one cannot be mounted
until this other is (I was tempted to use the notion of the dependee
and depender/dependend here, but this is always confusing, I think):
- layered mounts where one FS is mounted into the namespace of
another
- loopback (lofs) mounts which need another FS as their "device"
As a first effort to solve these issues "once and for all", I have
written
- A simple metaset take/release method (trivial)
- and a proptotype of a generec mount method
I would like to introduce the latter. Here's the general idea:
- Every mountpoint should be a service. If it depends upon other
mountpoints, SMF dependencies should be used
- What is now in /etc/vfstab should be in SMF, but to make things
easy, I would like a sync tool which generates an SMF config from
vfstab, similar to inetconv.
- This could replace or at least amend
svc:/system/filesystem/local:default and
svc:/network/nfs/client:default .
The prototype which I have finished so far converts entries from
/etc/vfstab to SMF and automatically creates dependencies. To mark
entries which should be handled by SMF, I used the keyword "smf" in
the mount at boot column of /etc/vfstab.
Here's the prototype in action:
* Create a vfstab with dependencies:
new-eclipse:~# grep smf /etc/vfstab
/dev/md/dsk/d20 /dev/md/rdsk/d20 /home ufs 2 smf
logging,noatime
swap - /mnt/test tmpfs 2 smf
-
/home/a/lib - /home/test lofs 2 smf
ro
/usr - /home/a lofs 2 smf
ro
swap - /home/a/lib tmpfs 2 smf
-
- /home/a depends upon /home
- /home/a/lib depends upon /home/a
- /home/test depends upon /home/a/lib and /home
/home/a also depends upon /usr, so for the prototype all mount
services also depend upon svc:/system/filesystem/minimal. For the
prototype, mount dependencies are only created for "mount at boot =
smf" vfstab entries.
* of these, only /home is already mounted:
new-eclipse:~# df -h
Filesystem size used avail capacity Mounted on
/dev/md/dsk/d10 20G 18G 1.7G 92% /
/devices 0K 0K 0K 0% /devices
ctfs 0K 0K 0K 0% /system/contract
proc 0K 0K 0K 0% /proc
mnttab 0K 0K 0K 0% /etc/mnttab
swap 4.9G 1.2M 4.9G 1% /etc/svc/volatile
objfs 0K 0K 0K 0% /system/object
fd 0K 0K 0K 0% /dev/fd
swap 512M 1.1M 511M 1% /tmp
swap 4.9G 72K 4.9G 1% /var/run
/dev/md/dsk/d20 50G 39G 10G 79% /home
* Run a create-smf-services-from-vfstab script:
new-eclipse:~# bash /home/slink/smf-mount/mount-simple-admin.sh
* ... and there you are:
new-eclipse:~# svcs -a | grep filesystem/mountpoint
online 11:40:31 svc:/system/filesystem/mountpoint/home:mount
online 11:40:31 svc:/system/filesystem/mountpoint/home:fsck
online 11:40:33 svc:/system/filesystem/mountpoint/home/X_a:mount
online 11:40:35 svc:/system/filesystem/mountpoint/home/X_a/lib:mount
online 11:40:37 svc:/system/filesystem/mountpoint/home/test:mount
online 11:40:38 svc:/system/filesystem/mountpoint/mnt/test:mount
an fsck instance ist created for moutpoints of an fstype which
supports fsck'ing.
(side note: SMF does not accept FMRI components with just one
character, so I am working around this by renaming the FMRI, e.g.
/home/X_a for /home/a -- I have already opened a bug for this, no
bug id yet)
new-eclipse:~# df -h
Filesystem size used avail capacity Mounted on
/dev/md/dsk/d10 20G 18G 1.7G 92% /
/devices 0K 0K 0K 0% /devices
ctfs 0K 0K 0K 0% /system/contract
proc 0K 0K 0K 0% /proc
mnttab 0K 0K 0K 0% /etc/mnttab
swap 4.9G 1.2M 4.9G 1% /etc/svc/volatile
objfs 0K 0K 0K 0% /system/object
fd 0K 0K 0K 0% /dev/fd
swap 512M 1.1M 511M 1% /tmp
swap 4.9G 72K 4.9G 1% /var/run
/dev/md/dsk/d20 50G 39G 10G 79% /home
/usr 20G 18G 1.7G 92% /home/a
swap 4.9G 0K 4.9G 0% /home/a/lib
/home/a/lib 4.9G 0K 4.9G 0% /home/test
swap 4.9G 0K 4.9G 0% /mnt/test
* Check dependencies:
new-eclipse:~# svcs -l $(svcs -a | grep filesystem/mountpoint| awk '{ print
$3 }')|egrep '^$|^fmri|dep\end'
fmri svc:/system/filesystem/mountpoint/home:mount
dependency optional_all/none svc:system/filesystem/mountpoint/home:fsck
(online)
dependency require_all/none svc:/milestone/single-user (online)
dependency require_all/none svc:/system/filesystem/minimal (online)
fmri svc:/system/filesystem/mountpoint/home:fsck
dependency require_all/none svc:/milestone/single-user (online)
dependency require_all/none svc:/system/filesystem/minimal (online)
fmri svc:/system/filesystem/mountpoint/home/X_a:mount
dependency require_all/none svc:/system/filesystem/mountpoint/home:mount
(online)
dependency require_all/none svc:/milestone/single-user (online)
dependency require_all/none svc:/system/filesystem/minimal (online)
fmri svc:/system/filesystem/mountpoint/home/X_a/lib:mount
dependency require_all/none
svc:/system/filesystem/mountpoint/home/X_a:mount (online)
dependency require_all/none svc:/milestone/single-user (online)
dependency require_all/none svc:/system/filesystem/minimal (online)
fmri svc:/system/filesystem/mountpoint/home/test:mount
dependency require_all/none
svc:/system/filesystem/mountpoint/home/X_a/lib:mount (online)
svc:/syste\m/filesystem/mountpoint/home:mount (online)
dependency require_all/none svc:/milestone/single-user (online)
dependency require_all/none svc:/system/filesystem/minimal (online)
fmri svc:/system/filesystem/mountpoint/mnt/test:mount
dependency require_all/none svc:/milestone/single-user (online)
dependency require_all/none svc:/system/filesystem/minimal (online)
Please note that the home:mount instance depends on home:fsck
I also added properties to make not only the mount options
configurable, but also fsck. This is something I was missing in the
past in certain corner cases when the defaults used by /sbin/mountall
and friends were not suitable:
new-eclipse:~# svcprop svc:/system/filesystem/mountpoint/home |egrep
'^(fs/|mount/|umount/|fsck/)'
fs/type astring ufs
mount/device astring /dev/md/dsk/d20
mount/generic_options astring -
mount/point astring /home
mount/retry_overlay boolean false
mount/specific_options astring logging noatime
umount/generic_options astring -
umount/retry_with_force boolean false
umount/specific_options astring -
fsck/device astring /dev/md/rdsk/d20
fsck/generic_options astring -
fsck/specific_options astring -
Status of the prototype:
* DONEs:
- sh code for SMF methods:
fsck : Based upon /lib/svc/share/fs_include.sh, but modfied to
support setting fsck options
mount : Using mountfs from /lib/svc/share/fs_include.sh,
additional support to try remount with -O if
svcprop mount/retry_overlay = true
umount: Simple umount with support for umount options
forced umount if umount/retry_with_force = true
- perl code to parse vfstab and extract dependencies
- admin script: bash code to do the basic vfstab to smf conversion
* TODOs (those which came to my mind)
- admin script: sync-with-vfstab -- modify properties if something
has been changed in vfstab, delete mpoints which have been
removed...
- automate dependencies to metasets and vxvm diskgroups
- test with zfs
- move ufs qouta-support from filesystem/local to mount methods
(:quota instance ?)
- finish all the details , ? rewrite admin script in perl ?
This mini project is really not in a state where is should be
published, but if people are interested, I will definitely publish
it. But first of all I would like to hear some opinions...
My questions:
- What do you think about this? Is this the right way to go? I believe
that it is, but maybe someone has a better idea?
- If this is something that the world needs, I would like to make this
an official opensolaris (mini-) project. Who would help to set this
up? Who would participate? Would Sun support this concept?
Nils
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