Edit: I enjoy crazy projects like this one.
Originally posted May 22, 2012 on AIXchange
A customer was looking to restore some data from an old LTO1 tape. The tape was created in 2005 with versions of AIX and Tivoli Sysback that were common back then. Since the customer no longer had hardware that could read the tape, I was asked if I could help retrieve the data.
An LTO3 tape drive can read LTO1 tapes, so I figured I’d look for that hardware rather than try to scrounge up an LTO1 drive. I contacted IBMers Jeff Werner and Pete Dragovich. From their Chicago lab, they use all kinds of leading-edge and vintage hardware and software to conduct customer-initiated projects and training activities. For instance, they recently performed a simulated HMC update (from 5.2.1 to 6.1.3) for a customer that lacked its own test box. They’ve also recently done a couple of proof of concept (POC) projects, one to simulate failover with IBM’s PowerHA high availability solution and the other involving SLES 11 Linux on POWER6. I figured if anyone could help me, it’d be Jeff and Pete.
I picked up the tape from the customer and brought it to the IBM lab. We built a POWER4 server with an old version of AIX and loaded the Tivoli Sysback code along with the tape utilities we needed for our LTO drive.
After getting everything ready, we loaded the tape, ran /usr/sbin/readsbheader –Nd –f/dev/rmt0 –l, and waited for a list of information. Instead, we immediately got errors. The volume label could not be read. After searching online, we discovered we could run commands to move the tape around and try to read some tape labels, but then we got I/O errors.
Fortunately, the customer had made two copies of the backup tapes, so I picked up the second tape. At that point, I was told that they’d used an unusual block size. That turned out to be the key. We tried 0, 512, and 1024, but hadn’t thought about 262144. Once we changed the block size, we were able to restore the data and all went as expected.
With the data restored, we copied it to a Windows machine to burn a DVD copy of the data. The customer then loaded the DVD onto their own Windows machine, and sent it to their server via FTP.
Some takeaways from this project: If you’re archiving data, either keep the hardware and software that’s capable of reading it, or periodically transfer important old data to newer media. And if you use a different block size when writing data, be sure that’s documented—preferably on the tape itself.
I enjoy solving problems, and this was no exception. Now if I’m asked to restore an old Sysback tape, I know I can do it—provided Jeff and Pete are again willing to lend me a hand.