Hi, I was curious what software people are using to backup AREV with? We are a 24 x 7 operation and so we have AREV constantly running and I was wondering if any one had any recommendations on a good open file backup software that runs with Novell 6. I read in some old posts that St. Bernard was a good choice, just wondering if anyone else could comment on whether or not it still is. Thanks.

I have a client using Backup Exec (Veritas/Symantec) on Netware 6.0x with ARev using the NLM.

They normally do not have open files during the backup but have now and then. Backup seems to work fine, but ARev files while open, may not have been updated during the backup.

I have not had to restore from an open file save so I cannot tell how that would go.

I don't know anything about St. Bernard.

I don't thing a software which does not know AREV philosophy can backup it properly. You must lock the file and backup .LK and .OV files than unlock it.

If the backup backups the .OV, .LK files separately without informing AREV not to update them in between, the data corruption can be expected (not regularly, but some times).

(Access to full group in .LK file causes simultaneous changes in .LK and .OV file, state of one file before and the other after does not allow to reconstruct the group.)

Are you familiar with St. Bernard? With this software, you can associate file types with each other. The software will take a snapshot of the files that are associated with each other. The backup will proceed using the state of the files as of the time the snapshot was taken. The same snapshot is used for all associated files.

IO continues, and St. Bernard manages the changes, effectively caching them until the backup completes, then committing them to disk.

Or at least that's how I remember it.

What I'd be concerned about is whether the image on disk accurately constitutes a good snapshot if something like the NLM, which does its own caching is used. If the NLM is configured not to cache writes (I think this is possible) then I think St. Bernard should be a viable option.

Note: I have not used St. Bernard myself. Also, I don't think it's actually backup software but a utility that allows ANY backup software to backup open files without causing the kind of temporal distortions you refer to.

Unfortunately if caching access to pair of .LK,.OV files starts in the time when one of .LK files was updated and the other is going to, the result will be corrupted file as described in my previous post.

The backup software must be informed the table is flushed before the process can start. Caching the access from this point allows users to continue their work so it reduces the risk much more but it does not prevent it!

Some thoughts …

MFS which logs stations starting update and waiting for their end can be useful, even read modifies the .LK,.OV files …,

how to set timeouts? Modifying such MFS not to allow the access when some global flag is set by backuping SW, and when last station finishes update resp. is timeouted flag for backuping software can be set to start caching, when backuping software informs by reseting the flag the caching starts, further updates are allowed.

Such a scenario seems to be safe.

The backup need know nothing about flushes. The whole idea behind open file manager is to allow backup software to be ignorant. But perhaps you were referring to the open file manager as the backup software.

In any case, I believe your concerns have been addressed by the software, but you'll have to read up on it carefully or perhaps speak with someone with more technical knowledge on how it works to fully understand how it works.

The main point I'm trying to make is that the software was designed specifically for this purpose. I know there have been Arev people who have successfully used it. Unfortunately, I don't know who they are, or I would have cited them as a reference.

I've also not used the product, so please take my posts as an invitation to start research not as any sort of final word.

I wouldn't be surprised if the product doesn't work when Arev is used with the Revelation NLM. On the other hand, maybe because it's an NLM gives the software a hook of some sort that Open File Manager can use to ensure the data is in the desired state. I just don't know.

We use Backup Exe (Novell) but there are three problems which we solved by not being quite a 24/7 operation:

1. Potential for locking of one particular LK or OV file of the pair can cause arev level corruption if the other side of the pair is changed by arev while it's mate is locked. Rarely does this happen. shhh….

2. Locking by the backup software gives the user or batch job a "in use locked" message, halting the user or job. Especially pesty with unattended overnight batch jobs. This is the most common problem.

3. Referential integrity across sets of tables. Example Customers and Orders. We backup Customers, then get an order for a new customer, then backup Orders. Obviously the Customers backup is missing that new customer, but the Orders backup has the order. We expect this might happen from time and time and we'll worry about it when we have to restore….

Our network guy figured out how to get Backup Exec to write a DOS file out "backup.flg" when it starts. We have an arev function that does an Arev Initdir on this filename (and path) and then a dirlist(). If we get something back, it means that backup is running. Out network guy then figured out when backup is done, how to get it to delete the backup.flg file.

Our arev batch jobs then either,

a) aren't scheduled to run when we guess backup is running

OR

b) make use of this function to check the status of backup, and if it is running to go into 'no updates' mode or not start. Some batch jobs cache to osfiles which get processed after backup is done.

We do backup when there are no users on-line.

Once and a while the flag either doesn't get set or doesn't get cleared….ouch.

Please let us know if you found St. Bernard to be a viable option, it sounds interesting!

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