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February 10, 2010

Directions on Using Store vs. Buldacct

Editor's. Note: 3000 experts have been asking what would our Homesteading Editor Gilles Schipper do while using the 3000's store directory option, rather than invoking the buldacct program to make clean backups. He weighs in with some sound advice.

By Gilles Schipper
Homesteading Editor 

The confusion surrounding the use of the ;directory store option versus the buldacct directory creation program is common. I believe it stems from the fact that in order to benefit from the store ;directory option, one has to utilize the option almost perfectly in both the store and the restore following a system INSTALL.

Consequently, it becomes much easier to fall back on the buldjob options to re-create the directory -- although that option is inferior.

In order to be able to effectively utilize the directory option, the first thing that must be done properly is to ensure that the appropriate ;onvs= option is also used in the case where user volumesets are utilized. Otherwise, the non-system volumeset directories do not get restored after the INSTALL since they are not on the tape.

But even if the store part is done correctly, the other opportunity to go wrong presents itself during the reload process.

The proper procedure during reload is as follows:

1. perform INSTALL
2. restore ;directory from tape
3. re-create disk and volumeset environment via VOLUTIL

Then -- and this where many go wrong,

4. Again restore ;directory from tape (this re-creates the volumset directory environment on the master volumes for all user volumesets for those utilizing it)

and then

5. restore files
6. reboot with start norecovery (to enable network functionality)

Of course, for those that do not utilize user volumesets, the directory option becomes much less error-prone. And, for those that utilize third-party backup utilities, the ;directory option -- as utilized in the MPE store command -- is generally replaced with a similar option in the various backup utilities.

However, the bottom line is that for those that utilize the MPE store command to perform their backups, the properly-used ;DIRECTORY (and, if appropriate) corresponding ;ONVS= options) -- together with correct restore procedures as indicated above -- will get the desired result 100 percent of the time.

Notwithstanding, of course, any tape issues occuring, which would be problematic no matter which directory re-creation option is used.

The bottom line is that the proper way to perform a full backup if using the MPE backup facility:

:file t;dev=tape
:store /;*t;partdb;directory;onvs=mpexl_system_volume_set,big;

Of course, upon further reflection, and better than the store command: use sysgen to create a backup tape that not only contains all files, but also the SLT -- so that this one tape alone can be used to INSTALL and RELOAD your system. The use of sysgen for such purpose will require use of an indirect file.

08:51 AM in Hidden Value, Homesteading | Permalink

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