Back up Services For Users of the Solaris and Linux Operating Systems
The Computer Center offers the following data back up services to
increase the safety of the data used by independent Solaris and Linux
workstation owners. (This service is included at no additional fee for those
who purchase our continuous workstation maintenance services.)
The growing sizes of hard disk drives and the data stored on them makes it
difficult and time consuming for the average person to back up large
quantities of data (i.e. greater than can be burned onto a CD (650 Mbytes) or
DVD (4.5 Gbytes)). We can use our existing back up infrastructure to provide
disaster recovery data protection through regular back ups for independent
Solaris and Linux users.
We will make back ups to tape twice a week, (Monday and
Thursday nights at 9:00pm) for up to 200 Gbytes of data per computer, and
retain that data for about three months.
If you wish to purchase this service, have any questions or a desire
to back up more than 200 Gbytes per computer, please send email to
request@pha.jhu.edu after reading through this entire page.
Pricing
The rates we will charge are based on the quantity of data per computer.
- From 0-20 Gbytes, $10/month
- From 20-50 Gbytes, $16/month
- From 50-100 Gbytes, $22/month
- From 100-200 Gbytes, $32/month
This price includes one free restore request per month per computer.
Additional restores will be $10 each.
These rates may be changed based on our operating experience.
To reduce the cost of the service, we will not be accounting for the exact
volume of data being backed up every month. We will pick a data size category
when configuring your computer for this service, and then charge that same rate
every month. We might double-check the actual volume once in a while and
adjust your rate.
We don't aggregate all of the data on all of a client's multiple computers
into a single lump sum because the number of computers involved is related to
the amount of effort required to back up and restore data. (More computers
means more hard disk drives to fail, more back up software to install and
configure, and more users to accidentally delete data.)
Our Tools and How They Work
Our back up infrastructure consists of:
- back up software for UNIX computers called Amanda, a product of the
University of Maryland,
- a back up server computer,
- a tape jukebox containing two SCSI AIT-2 8mm tape drives and 22 tapes
- a hard disk RAID-0 striped disk array containing four 36 Gbyte SCSI disk drives,
- a set of tapes dedicated to this purpose, and
- the knowledge of how to use them to perform automated back ups.
AIT-2 tapes hold 50 Gbytes each. We use a set of them so that, for a given
amount of data, we can hold one or more copies of the data, and modified
versions of that data, for a few months.
- We install a portion of the Amanda software on each computer to be
protected.
- When a back up session is conducted, our back up server contacts each
client computer and retrieves the data. Sometimes this is all of the files
in a file system (called a full back up), and some times it is the files which
have been modified since the last full back up was done (called an
incremental back up).
- Those files are stored on our 120 Gbyte RAID-0 striped disk array until they can
be written to a tape drive. This increases the overall back up speed and
reduces wear and tear on the tape drive, because data can be transferred to
the tape drive continuously at hard disk speeds rather than network speeds.
- After a back up session is completed, the tape is removed from the drive.
It is kept for a period of time, then re-used.
Details and Caveats
This is NOT A DATA ARCHIVING SERVICE meant to free up space on your
hard drives! We will not retain the data for long periods of time or
guarantee that it can be restored. (So it should not be the only copy
of the data.) This service will protect against hard disk failure or
accidental file deletions over the period of several months.
The following constraints also apply:
- The Amanda software works on a file system basis. This means that
the software can only backup the entire file system, not just subdirectories
of it. You may need to reorganize your data to avoid our backing up
material you don't want to pay for.
- The maximum size of the file system has to be smaller than the capacity
of our tape drives (50 gigabytes).
- There is a limit of one free data restore request per month per computer
to limit staff labor time and keep prices low.
- Our Amanda software has to work on your computer's operating system
revision. If we cannot get it to work, then you won't be charged anything.
- We have to have the root password on your computer.
- Your computer needs to be continuously connected to the departmental network.
- Laptop Linux computers can be backed up; however, they need to be connected
to the departmental network during the backup periods.
- If you have a lot of data, and you need to have it restored from tape, you
will need to provide the disk space for us to restore onto -- for example, if
your hard disk dies, we cannot give you your data until you have a new place
to put it. (We just don't have big chunks of disk space lying around unused.)
- If our tape jukebox dies, we may have to discontinue the service unless we
can get the funds to replace it. (We will still be able to restore previous
data using a stand-alone tape drive.)
