Op 25/09/2012 2:03, James Harper schreef:
>> Hello all,
>>
>> This is not likely a bacula questions, but in the chance that it is, or the
>> experience on this list, I figured I would ask.
>>
>> We've been using LTO3 tapes with bacula for a few years now.  Recently I've
>> noticed how variable our tape capacity it, ranging from 200-800 Gb.
>>    Is that strictly governed by the compressibility of the actual data being
>> backed up?  Or is there some chance that bacula isn't squeezing as much
>> onto my tapes as I would expect?
>>
>> 200Gb is not very much!
>>
> I don't think this explains your issue, but LTO drives will write the data to 
> the tape, and then immediately read it again (the read head is placed such 
> that this is possible). If the read is bad the drive will rewrite the data. 
> This ensures that you get a good write, but obviously decreases the effective 
> capacity of your tape.
>
> Your tapes would have to be pretty worn out to drop the capacity to 25% 
> though.
>
> The tape and/or drive should record the margin and other figures, but I don't 
> know of any Linux tools to read that information.
>
> James
The tools depend on the brand. For HP drives ltt is nice and works 
flawlessly on linux command-line. It reports drive errors, tape errors 
for the past 4 tapes, tape and drive margin, and a lot of other info.
http://h18006.www1.hp.com/products/storageworks/ltt/

I know IBM has their own tool (ITDT), but as far as I know there is no 
command-line version of their tool.

Other brands, no clue.

Regards,
Jeremy

 **** DISCLAIMER ****
http://www.schaubroeck.be/maildisclaimer.htm

------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
_______________________________________________
Bacula-users mailing list
Bacula-users AT lists.sourceforge DOT net
https://lists.sourceforge.net/lists/listinfo/bacula-users