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July 24, 2012

Make backups, but a CSLT is just as vital

Many homesteading HP 3000 shops are working with limited system administration. If you're reading this blog, that probably doesn't apply to your own 3000 shop. But you can pass on advice about backing up to any 3000 site you know. A backup of applications and databases isn't enough.

The CSLT needs to be fresh and available, too. The Custom System Load Tape tells the 3000 how the configuration is set up for devices attached to the system that you're restoring. (The original SLT that was distributed from HP has a generic configuration. This customized SLT reflects your physical configuration of your specifically-built system.) Also referred to as a boot tape, it contains the system load utilities, diagnostic subsystems, base system files, and other HP system files such as IMAGE, FCOPY and EDITOR.

A CSLT is generated with the system generator (SYSGEN) utility. You can build a CSLT for individual systems, each with a different configuration, after updates. These configurations tell the 3000 what other volumes are available to accept data. You can also put a full backup on the end of a CSLT, but it's better to have that backup on separate tapes. (Separating a backup from the CSLT also speeds up creating a CSLT.) Consultant Paul Edwards advises that managers make a CSLT at least every other time during a backup, plus having two tape drives on each system. "Being paranoid makes for a good system manager," he says. "If you're not paranoid enough, you better have a good resume."

Overlooking the CSLT is so common that even some admin pros have done it from time to time. For one such pro, an A-Class 3000 was recently rebuilt and had its apps consolidated. But the rebuilt system didn't have its CSLT freshened, which was discovered when the boot volume failed. 

We lost LDEV1 in the 'system' volume-set. The apps and databases are fine, but I'd neglected to make a fresh CSLT once the rebuild/configure/setup was complete. Fortunately, all the data volumes are protected with Mirror/iX -- but rebuilding the system volume accounts, network config, administration jobs and so on has been a pain.

An honest mistake like this is not one you need to make yourself. Even if, as another 3000 consultant notes, your shop has gone into Frugal Mode while it makes in-house moves. You have the right to be wrong in Frugal Mode. But you really don't want that right, unless you've got plenty of extra time.

"This is not a mistake I'll ever make again," said our CSLT rebuilder. "Until it's complete and stable, I now make a new CSLT at the end of each day's changes (in addition to the regular backups we do as Store-To-Disk, and then FTP to a NAS). Hopefully I'll never have to go through this hassle again."

AUTOINST updates temporary copies of the system libraries and then creates a CSLT. This can take up to two hours. One set of instructions to do this is available in HP's MPE/iX 7.5 Maintenance Manual. The process hasn't changed much from the 6.0 release of MPE/iX, either. We've got a pointer to each manual; just search for "CSLT" in each PDF file.

We've previously published a paper by Gilles Schipper on the use of BULDACCT versus the STORE command while backing up. The ;DIRECTORY and ;ONVS= options are a key there. What's more, one of our most prodigious contributors Brian Edminster is sketching out a technical, but easy-to-use, Automation of Backups and Effectively Eliminating Use of Tapes article.

Do all the backup that you need when protecting that HP 3000. It's a computer that established the gold standard for recovery in case of powerfail situations. But the success of its backups falls in the lap of the system's managers or owners. (Running CHECKSLT from the TELESUP account will verify if a CSLT is still good enough to boot your system. You'll want that CSLT to run on any tape drive, not just the one it runs on. Alignment issues kick DDS drives out of service regularly.) Don't forget about keeping your CSLT healthy.

04:13 PM in Hidden Value, Homesteading, Migration, User Reports | Permalink

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