There are several filesystems available. The table below summarizes most of them.
|Filesystem||Purpose||How to access||Notes||Backups|
||ZFS, available with NFS, SMB and AFP||ZFS snapshots
||ZFS, web-accessible, available on PCs||ZFS snapshots
||replace NODENAME with hostname minus domain.
remote replication or none
These all have quotas except for the
/NODENAME disks are available on other hosts through NFS as
cd /m/NODENAME to access one.
Available disk space can be seen by using the
dfcommand. For example
. for info on the filesystem you are currently in or
The current quota policy on the main research network for home directories is 25GB limit for undergrads, 50GB limit for graduate students (Staff, Professionals, etc.) and 100GB for faculty. The mail spool also has a quota (1GB, 2GB and 4GB respectively for undergrads, grads and faculty). Home directories are found under /usa/$USER. Additional space is available (intended for web usage) on the main research network under /usb/$USER. This space also has a quota, that varies according to the users’ status.
Note: Research home directories were upgraded to larger quotas with ZFS in Summer 2009.
To list your current quota on any filesystem use ‘
df -h .’ while in that
filesystem. Your limit will be listed under size and what you are using and
have available will also be listed. All core ECE/CIS systems are using ZFS.
For ZFS filesystems the
quota command does not apply. The
df command must
be used instead. Also read below about ZFS for more info. In the case of samba
filesystems Windows will also report the amount of space used and available.
ZFS is a new file system from Sun that has some revolutionary features. Most of those features are of interest to admins and those interested in filesystem research.
With ZFS, instead of having many users per filesystem and having quotas based
on the user ID, each user has their own filesystem. The
quota command does
NOT apply to ZFS filesystems. Instead, the
df command should be used to see
how much space is available. Please pay attention to your space free. Also,
read below for how snapshots affect disk space usage.
If you run into quota exceeded messages you can truncate a large file by
/dev/null to the file, and afterwards you should be able to
remove it as normal. ex:
cat /dev/null >! ~/bigfile. If this does not work
start a bash shell and try the command
:>! ~/bigfile which should set the
file to zero length.
There are other solutions as well, please read the section on Snapshots before posting a help request.
ZFS supports snapshots, which are read-only images of the filesystem at the
time the snapshot is taken. They are available under the
directory from the base of the filesystem (every user has their own ZFS
filesystems). For example, for your home directory look in
.zfs directory may not show up in a directory
ls -a as it is hidden, but changing to it is possible. In there
you will find directories with the name of 12, 18, Mon, Tue … Sat, Sun. The
12 snapshot is taken during the noon hour, and the 18 snapshot is taken during
the 6pm hour. They are named like this to allow future hourly snapshots to be
possibly included. There are also snapshots for each day of the week which are
taken during the 11pm hour. Each day during the noon hour the snapshot from the
previous day is destroyed and a new one is taken. The same is done during the
6pm hour. During the 11pm hour the snapshot from one week ago is destroyed and
a new one is created. When a snapshot is taken no additional space is required.
However, as the filesystem changes, copy-on-write is done and will cause
snapshots to use space which will be counted toward your quota.
When a snapshot is taken no space is initially used by it as it is a read-only reference for the current filesystem image. As the actual filesystem is changed new blocks are allocated and are counted toward the quota use. Users cannot delete individual files from a snapshot. When a file is removed, that made it to the 11pm snapshot, it does not free space up until one week later.
If you are close to your quota and reach the limit you will receive disk quota
exceeded or filesystem full errors. While you can not delete individual files
from your snapshots you can now delete the snapshot on ACAD and Research
systems using the
rmdir command. Ex:
rmdir ~/.zfs/snapshot/Mon would delete
your Monday snapshot and free up any space used by it.
Special note for Windows users of samba filesystems:
Some example uses of snapshots for users are:
ZFS uses checksums so data reliability from disk is guaranteed. These filesystem are also resilient to single disk failures, as we configure them (uses raidz which is an improvement of raid5 or raidz2 which is raid6 like). When a disk fails (or is failing) we are notified and it can then be replaced with users not noticing.
If a file is deleted, or you need an older version of a file it is possible
that it can be retrieved from a backup. First, if the filesystem the file
resided in uses ZFS look in
Remember, your file must have existed when the snapshot was created in order to be restored. If you create a file and delete it five minutes later, it most likely will not be recoverable.
In order to protect yourself from inadvertently removing files you may wish to look into the following:
Another thing to consider, if you don’t want to alias rm, is to look into the
tcsh rmstar feature.
set rmstar will cause tcsh to prompt «
Do you really
want to delete all files? [n/y]», before removing all files. But be warned
that this only works if rm is not aliased, exactly
rm * is done and with tcsh
Solaris implements ACLs (Access Control Lists), which give users much more
flexibility to share files, than what the standard UNIX permissions offer. ACLs
of a UFS file can be viewed with the
getfacl command. UFS ACLs are set and
manipulated with the
setfacl command. On ZFS filesystems, ACLs are viewed
ls -v, and set and manipulated with
chmod A.... The man pages of these
commands explain the details.
Please continue to the ACLs page for more information and examples of using ACLs.
Unix home filesystems are available through the samba server,
\\smb1.eecis.udel.edu\username for research homes and
\\smb1.acad.ece.udel.edu\username for acad can be mounted on PCs. For more
info please see the ECE/CIS SAMBA Mini-Howto.
Also, the research /usb filesystem (for web pages) is available through samba
The home filesystems are also available over AFP. To see how to connect see AFP.
For more information, see our backups page.