Getting into tape backups (Part 1)
Part 2 of my Poor man's UPS has not showed up and probably never will; so, let me write about something I did recently.
Unless you were born around the time when people were still talking about the differences between PC-AT and PC-XT and BBC Micros were the cutest thing around, tape storage must be pretty antiquated for you. Allow me to contradict you though, and tell you, how cool tape storage is!
Why tapes ?
Tape storage is common sense, it's how you would design a storage solution if you started with nothing. What does that mean ? Well, data is pushed down a pipe sequentially, the imaginary picture of your data you have in your mind is exactly how tape would store it. Of course, magnetic media needs to be handled with care but tape storage is designed to be scalable and stable and you can have a functional backup system with simple UNIX tools. There are other exceptions too, such as LTFS that treats tape storage just as regular file system. It's impressive, but it's also overkill to treat everything as a regular file system. Just like programming languages – everybody wants to write their own :)
LTO
If you are getting into tapes, you definitely want LTO (Linear Tape Open) tapes and drives. It's backed by a few great ones and the technology still sees revisions; the latest being LTO-9 which can store a whopping 45 TB of compressed data in a single cartridge.
Now, when you are buying tape drives, look for the latest LTO drive that you can afford (they are backwards compatible). Also, the big names are usually manufactured by IBM and rebranded (such as the Dell PowerVault that I own and what this post covers) and they are known to be very reliable. You will also notice that internal mount drives are usually cheaper than external drives; but beware, internal drives need proper ventilation and cooling. A safe bet is to always go for a drive with external enclosure.
Connectivity
Almost every external tape drive I have seen in the wild and on the used market uses SAS. So, it's a must that you have a unused sas port on your system. Nothing exotic, something like a LSI SAS 3008 would do. Older ones should be fine too but cheaper and maybe, a bit unreliable.
Getting a used tape drive
Now that the basics are done, it's time to move on to getting one. Your best bets are eBay auctions of enterprise equipments but there are two things I would stress – first, try to get your hands on a good brand (Dell/IBM or maybe HP), and second, unless there's a test report included, make sure there's a return period within which you can can test the system.
Testing it out
So, you have got one and set it up, it's time to make sure everything's ok.
Self tests
All drives should have some form of self tests. You will most likely need an empty cartridge for all tests. They can be run either via a combination of button presses or via an ethernet interface. At least, the PowerVault has one. Try to run all of diagnostics and make sure everything passes.
ITDT
IBM's Tape Diagnostic Tool is also a handy tool for running diagnostics and firmware upgrades. There's a good chance, your drive is supported (remember how I mentioned that IBM is the OEM for most drives ?) and if it is, you can run many of the diagnostics that the tool offers.
Firmware upgrades
Dell, for example, provides firmware for many of its drives but the requirements are somewhat esoteric to be able to run the executables. However, as long as you have a way to extract the firmware image, and ITDT supports your drive, you can use it to upgrade the firmware. For example, with Dell firmware, you can do something like:
./Tape-DrivesFirmware64VG4LNM571_A07.BIN —extract firmware
which will extract the firmware image to the firmware/payload directory.
Once you have the firmware file(*.fmrz) you can use ITDT to install the firmware.
Using your tape drive
And that's it! Now you can use standard mt and tar commands to read and write data from/to your tape drive. You can also use well known backup tools if you wish. In the next part of this post, we will script a scalable backup strategy for our data using readily available unix commands such as tar, mt and family. Stay tuned!