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FileStorage

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1.  Filesystems available under Unix

There are several filesystems available. The table below summarizes most of them.

Filesystem	Purpose	How to access	Notes	Backups
/usa	Home directories	/usa/$USER	ZFS	ZFS snapshots, tape
/usb	Web directories	/usb/$USER/public_html	ZFS, web-accessible, available on PCs	ZFS snapshots, tape
/samba	PC data	/samba/$USER	Available on PCs, ZFS	ZFS snapshots, tape
/NODENAME	Local disks	cd /NODENAME	replace NODENAME with hostname minus domain. No quotas	ZFS snapshots, tape or none
/temp	Temporary space for Acad	/temp/$USER	Available on Acad hosts. For large and/or transient files.	None

These all have quotas except for the /NODENAME disks. The /NODENAME disks are available on other hosts through NFS as /m/NODENAME. Just cd /m/NODENAME to access one. NOTE: /NODENAME not available on McKinley 051 Lab systems.

Available disk space can be seen by using the dfcommand. For example df -h . for info on the filesystem you are currently in or df -h /m/NODENAME, etc.

Additionally, there is a filesystem for email that is available through imap that uses ZFS (with large quotas).

Acad hosts have a /temp filesystem that is shared and has a quota. A convenience link at /usa/$USER/TEMP that points to the users' /temp file system is made for users when the account is created. This filesystem should be used for large and or transient files instead of the home directories. This filesystem is not backed up and no snapshots are taken of it. Important files should be kept in your home directory which is protected with backups and snapshots.

The File servers started using ZFS in Summer 2006. Read the announcement for more info.

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2.  Quota policy

The current quota policy on the main research network for home directories is 1GB limit for undergrads, 2GB limit for graduate students (Staff, Professionals, etc.) and 10GB 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/$USER. Additional space is available on the main research network under /usb/$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 2006.

Quotas on the samba server, are 4GB for Faculty, 1GB for acad accounts and 2GB for everyone else. This filesystem currently makes use of ZFS.

To list your current quota status for /usb type "quota -v". Other commands that are useful for disk space info are du -k and df -k.

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 the samba filesystem Windows will also report the amount of space used and available.

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3. ZFS info

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. For those interested, info is available at Opensolaris.org.

3.1  Quotas

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.

3.2  Snapshots

ZFS supports snapshots, which are read-only images of the filesystem at the time the snapshot is taken. They are available under the .zfs/snapshot directory from the base of the filesystem (every user has their own ZFS filesystems). For example, for your home directory look in /usa/$USER/.zfs/snapshot and for your samba filesystem look in /samba/$USER/.zfs/snapshot. The .zfs directory may not show up in a directory listing using 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 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. You could run into a case where you need to put in a help request to have snapshots removed to free up space. If warranted, quotas can also be increased.

Special note for Windows users of the samba filesystem:

• It has been observed that Windows may think it is deleting files from a snapshot, but the file is actually not removed.
• Windows will show how much space is available in your filesystem.

Some example uses of snapshots for users are:

• If a file is deleted or changed during the afternoon you can go to the 12 noon snapshot and retrieve the file.
• If a file was deleted on Friday and you do not realize until Monday you can use the Thu snapshot to retrieve the file.
• The 6pm snapshot can be used similarly and is also used for nightly backups to tape.
• Virtually eliminates the need for using undelete as snapshots for the past week are available online in the filesystem. Undelete may still be used to retrieve files from tape that were deleted more than a week ago.

3.3 Reliability

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). When a disk fails (or is failing) we are notified and it can then be replaced with users not noticing.

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4.  Recovering deleted files (from snapshots or from tape)

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 .zfs/snapshot.

Nightly backups are also done for most filesystems to tape. (backups of laptops are done during the day). A request for restoring a file from tape can be done by requesting the file to be restored using the Help System. After logging in choose "Request File from Backups" on the left.

Remember, your file must have existed when the snapshot or tape backup was run in order to be restored. If you create a file and delete it five minutes later, it most likely will not be able to be recovered.

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5.  Preventing inadvertent file removal

In order to protect yourself from inadvertently removing files you may wish to look into the following:

• alias rm to rm -i
• alias mv to mv -i

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 not csh.

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6.  Access Control Lists (ACLs)

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 with 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.

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7.  Using Samba server from PC

The samba filesystem is available on Solaris hosts through /samba/$USER. The /samba directory is managed through the automount daemon and an ls should not be done in it. Using ls in /samba/$USER and any subdirectories is fine though. The samba filesystem utilizes the new ZFS filesystem technology.

This filesystem is available through the samba server, smb1. Once authenticated \\smb1\username 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 using the \\smb-www.eecis.udel.edu\username.

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8.  Backups

Backups of Unix systems maintained by ECE/CIS are performed nightly to tape. For ZFS filesystems, the 6pm snapshot is used. For other filesystems the live filesystem is used. For these backups we use Amanda.

8.1  Data Retention Policy

We do separate archiving of important SERVER data filesystems (home directories, email, web, etc) quarterly. These tape archives are kept for a period of five years. Client computers, PCs, Desktops, laptops (/NODENAME, etc.) are not archived. If you have important archival data, please make sure it's on a Server system. Daily backup tapes are in a 30 to 60 day tape cycle, so if data is over 30-days old, but not on a quarterly archive, it may not be able to be recovered. ZFS snapshots (such as those on the laptop virtual-tape backup system) have separate retention policies depending on available disk space and usage. See the Backup Status section to check and submit a Help Request question for any specific data retention issues not covered.

8.2  Backups of Linux, *BSD, and MacOS Systems

We also will backup Linux and *BSD systems that are maintained by users with Amanda. To do this the user should install Amanda, and give the operator user passwordless ssh access to the system from pitch-black.eecis.udel.edu. The public DSA key for the system is here. The operator user also needs access to read the raw disk devices. Ryan Bickhart has written Instructions for FreeBSD.For more info and to have this enabled use the Help System.

8.3  Backups of Windows Systems

Another tape config is run during the day to backup Windows PCs using Bacula. To have a PC added to this, or to check on the status use the Help System. If you are already scheduled for daily backups, there will be a bacula icon (example) in your Windows system tray. Clicking on this icon will open the summary for recent backup attempts. If the status field indicate an error over a period of many days then the Help System should be used to attain further assistance.

8.4  Backups of Faculty Laptop Systems

There is a Virtual Tape System (VTS) available for backing up faculty laptops (100GB+). A script has been written to initiate backups from a client which can be manually activated or (ideally) scheduled to run automatically: other server/desktop backups are activated from the server, which isn't ideal for mobile systems which aren't always on the network. Feel free to request assistance through the Help System

To restore files from the Virtual Tape System, you can either mount the VTS on your computer or recover files from /backups/USERNAME on any EECIS UNIX system. To mount the VTS on a Windows client right click "My Computer" from the Start menu and select "Map Network Drive". Choose an unused drive letter and enter \\smb2.eecis.udel.edu\USERNAME as the "Folder". Note that USERNAME needs to be your EECIS login username, and if your username on your laptop is different, you'll need to click "different user name" and enter the appropriate information in the popup. To mount the VTS on a Mac client, from the Finder, select "Go->Connect to Server", and enter "smb://smb2.eecis.udel.edu/USERNAME" as the server address. Be sure to select "Registered User" and enter your EECIS username as your name (your full name may be pre-filled).

Regardless of how you locate your backups, you should normally see two folders. One folder will be named for your machine, and is where the most recent backup files are found. (Z:\MACHINENAME\cygdrive\c, for example). The other folder is named 'Archive' and points to an hierarchy of archived copies (Z:\Archive\snapshot for example). Note: archived backups may not be visible via SMB mounts and you may have to recover older files via EECIS Unix machines. The hierarchy is as follows: 12 & 18 are the previous Noon and 6pm copies, Mon through Sun are the Noon copies from those days this week, w0 through w7 are the Friday Noon copies from those previous 8 weeks, and finally the m0 through m2 are the end-of-month Noon copies for the previous 3 months.

8.5  Status of your backup

ECE/CIS users with university-owned systems can now see the status of their backup by visiting the Backup Information Page. From here, find the hostname of your machine, and hover over the hostname to see a summary of each disk on the computer. Click the hostname to have full detail of the backup status as well as reasons for failures. From this page, you can request a machine be added or removed from daily backups. You can also request a file restore from this page.

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