Question regarding FSM (fast search marks- fbackup)

[steven Burgess_2]

Hi all

As far as I am aware the fsm is placed onto the tape at the time of writing each file to tape

If I am incorrect please advise

I have an error message

fbackup reports FSM error(s) (exit code 2)

Exit code 2 errors are generally problems with media or drive etc

How is it possible to configure FSM (or is it?)
or are there other methods?

Any more info would be great

Thanks in advance

Steve

[Bill Hassell]

A Fast Search Mark is only defined for DDS tape drives. For DLT drives, file marks are used. The purpose of FSMs is to skip forward very rapidly (faster than the data can be read) as these marks can be seen in high speed mode. FSMs are recorded for every N number of files where N is defined in the fbackup config file. The default is every 200 files.

FSMs require a significant amount of space on the tape (in order to be seen at high speed) so the config file parameter filesperfsm should be adjusted much higher if you are saving millions of small files.

The error you are seeing is likely due to a drive problem but I would start with a clean tape. While DDS drives are backward compatible, it is not a good idea to use a lower-numbered tape in a higher-numbered drive (ie, DDS-2 tape in a DDS-3 drive), especially for writing. Use the same media that the drive supports.

[steven Burgess_2]

Thanks Bill

The drive is a DDS , it's in holland, whats the best way to find the DDS type apart from reading the label on the drive?

Have searched for the config file filesperfsm
where is this?

I've checked the index of the tape and performed a word count which returned 245232
files

What would you recommend as a setting in the config file

[steven Burgess_2]

Anyone?

[James R. Ferguson]

Hi Steven:

The 'filesperfsm' parameter is one of ten defined for 'fbackup' in the optional 'config' file (see the man pages for 'fbackup').

A default set of values for 'fbackup' are provided in the absence of a 'config' file as noted in these man pages. The defaualt values give quite poor performance in most situations since they are based on old tape technology.

The 'blocksperrecord' is very small by default and should be increased to something like <256>. The 'records' value should be doubled to <32> and the 'checkpointfreq' increased. Increasing the 'readprocesses' allows more processes to read from disk and fill 'fbackup's internal buffers faster, keeping the tape from slowing or stopping while waiting for more data.

Regards!

...JRF...

[Frank Slootweg]

> The drive is a DDS , it's in holland, whats the best way to find the DDS type apart from reading the label on the drive?

The best thing is the product 'number' (letter, four digits, letter(s), *not* the 'name' (i.e. "SureStore Tape 5000"). The product number should be on the label on the drive ('cabinet'), mostly on the back. Also a quotation, order, invoice, packing list, etc. could help.

Absent all that do a "ioscan -f [-H ...]" and report what it says under "Description".

[Bill Hassell · Accepted solution]

Sorry, I've been traveling...

man fbackup and then look for filesperfsm. You'll see it describes an *optional* config file. If you do not run fbackup with a config file, you will get very inefficient operation for modern DDS, DLT and Ultirum drives (default are for reel-to-reel 1/2" tapes). Here is an example of a config file appropriate for newer drives:

blocksperrecord 256
records 32
checkpointfreq 1024
readerprocesses 6
maxretries 5
retrylimit 5000000
maxvoluses 200
filesperfsm 2000

This file is also where you specify a script to be run when fbackup runs out of tape (typically used to run the mc command for moving tapes in a changer).

[steven Burgess_2]

Excellent, thanks Bill

I read James' reply last night , and should have looked at the man page for fbackup.

Also found a couple of web pages with regard to 'the mysteries of fbackup' which I found extremely interesting.

Backups have been failing for other reasons also, we have found that this system may be using an older version of our backup scheduler utility that we use from cron. The config file in that may be out of date. We are going to look at this.

Thanks everyone