Comparison of Backup Products
BRU is a modern replacement for tar (Tape ARchive). Many of the command line options for BRU are identical to those for tar, which means you can upgrade from tar to BRU fairly painlessly. In addition, XBRU, the GUI, is merely a front end: all XBRU does is build an appropriate command line and hand that off to the command-line executable.
One feature that is missing from BRU is the ability to use the GUI to build a command line, then export it for use in a script. This would be a very useful tool for the command-line-challenged.
The help is all on-line at EST, Inc.'s web site. This is great if you don't mind going on line to read your docs, because they are always the latest. What happens, though, when EST releases a new version? Will your help still point to the web pages for the version you have? Hey, guys: not everyone has a T1 connection to the Net.
Installation is straightforward. I got the demo version from the EST web site. It comes in a tar file. Copy it into its own directory, untar it and execute ./install. The installation script asks for information about your tape drives. It will ask you for the capacity (uncompressed) and rewind and non-rewinding device names. The devices ran with no further changes. However, there are sample device definition files for a number of drives on EST's web site.
You can run multiple XBRUs and simultaneously access different tape drives. This is great for backing up to multiple tape drives, but does not give the flexibility of Arkeia's flows.
Verification of a backup is very useful. EST thinks you should do it every time to verify the backup, and that's a good idea. Their autoscan feature makes it easy to build into scripts.
The professional version, which I did not review, will provide a database of files backed up, thereby eliminating the occasional need to read multiple tapes to find a given file.
One thing missing from BRU is support for tape changers. As I have not worked with tape changers, I can't comment on their reliability. But I'd rather have high enough capacity tape drives and arrange my backup schedule so I don't need a tape changer. Unfortunately (for system administrators, if not for users), the ability of hard drive manufacturers to wedge capacity into their products seems to exceed the ability of tape drive vendors to add capacity to theirs. So there may be a tape changer in your future.
Next in line is Arkeia, from Knox Software. Arkeia has a three-part design. The server resides on the machine to be backed up, and writes the backup with local file permissions and bits. The server backs up and restores files; the client runs one or more tape drives on a machine; and the user interface provides user control over the other two parts. The user interface comes in two flavors, command line and GUI.
One implication of this design is that Arkeia's Windows server, which runs as a native Windows process, can back up the registry as metadata, not as just another file. However, there has been some question about restoring registry backups on the Arkeia user's list, so if you run Windows in your shop, make sure you can do a full restore of the registry on a test computer before you are satisfied with Arkeia's performance.
There is nothing that says that any one component has to reside on the same machine as either of the other two. In my setup, I run both the user interface and the tape client on the same machine. I also run servers on that machine and each of the other four computers on the network.
This architecture makes possible what Knox calls “flows”. Most backup software simply walks a list of directories to back up. (The brain-dead backup applet that comes with Windows NT is a classic example.) Arkeia has each server feed its data to the client, so that multiple machines are backed up simultaneously. In my environment, each of the five computers is represented by a “flow”. The result is very fast backups: to my HP DDS 3 DAT tape drive, I get backups at a sustained rate of 57MB a minute, or 12GB in under four hours. That data rate keeps the tape drive streaming, which is important for tape and drive longevity. While I haven't tried it, you should be able to back up multiple machines to multiple tape drives. Under those conditions, Arkeia should optimize data flow to keep all of the tape drives streaming.
Arkeia builds a database of files as it saves them to tape. This is great because you can browse the contents of your tape library without having to mount each tape in sequence. It also has a weakness: Arkeia does not back up that database itself. That means if the file system on which the database resides goes south, you have to restore it from tape by reading each tape since the last total backup. My solution to this weakness is to use BRU to back up that file system.
When I first reviewed Arkeia for Linux Journal (April 1999, http://www.linuxjournal.com/issue60/3166.html), I reported excellent customer support. While I have not used the customer support recently, I must report some grumbling on the list about it. This grumbling indicates that Knox's customer support has gone downhill since I wrote the review. Perhaps the folks at Knox think that a list is an adequate substitute for good customer support; it is not.
Setting up Arkeia initially is a lot of work. You first define everything down to the individual tapes, which are lumped into savepacks, then the drives, etc. Defining a backup is a matter of selecting the savepack and the files to be backed up. Once you have done that, you can run a backup at any time, manually or at pre-defined times. The complexity of initial setup is the price of Arkeia's extreme flexibility. A “wizard-style” interface would be easier to use than the potentially confusing menus Arkeia uses. Short of that, the manual walks you through the process of setting up and running null device backups to verify your installation.
Arkeia is probably the most ported of the lot. If you have more than Linux and Windows NT, look at Knox's web site for a list of supported OSes.
One thing missing from Arkeia is the ability to verify a tape. Neither verification by comparison nor by checksum is available. All I have been able to do is a partial restore to another location and then comparison against the original, a process that verifies only a portion of a tape. Of the four products reviewed here, Arkeia is the only one with no form of verification.
Arkeia is priced on a per-seat basis. For a quote, visit the Arkeia web site. You can download a “personal” version. The latter is restricted to one tape drive and a fixed number of clients.
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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