Bacula-users

Re: [Bacula-users] About tapes capacity

2011-04-20 13:37:16
Subject: Re: [Bacula-users] About tapes capacity
From: John Drescher <drescherjm AT gmail DOT com>
To: Jason Voorhees <jvoorhees1 AT gmail DOT com>
Date: Wed, 20 Apr 2011 13:34:27 -0400
On Wed, Apr 20, 2011 at 10:31 AM, Jason Voorhees <jvoorhees1 AT gmail DOT com> 
wrote:
> On Wed, Apr 20, 2011 at 9:22 AM, Paul Mather <paul AT gromit.dlib.vt DOT edu> 
> wrote:
>> On Apr 20, 2011, at 10:17 AM, Jason Voorhees wrote:
>>
>>> Hi people:
>>>
>>> I'm running Bacula 5.0.3 with an tape library IBM TS3100 using LTO5
>>> tapes of 1.5 TB capacity each one. I have a simple question: If I run
>>> a job backup of a server that holds more than 1.5 TB (example: 2 TB of
>>> data), what happen when Bacula reaches the limit of the tape capacity?
>>> Does Bacula automatically change the tape?
>>>
>>> I'm not pretty sure about this because I recently ran a job backup of
>>> 2 TB and Bacula apparently just used one tape: have a look at my
>>> volume listing:
>>>
>>> * list volume
>>> ...
>>> ...
>>> |       5 | L5BA0005   | Append    |       1 | 2,058,019,117,056 |
>>> 2,059 |    2,160,000 |       1 |    5 |         1 | LTO-5     |
>>> 2011-04-19 20:58:51 |
>>> +---------+------------+-----------+---------+-------------------+----------+--------------+---------+------+-----------+-----------+---------------------+
>>>
>>> When the job started Bacula took the tape L5BA0005 and never required
>>> another one. As you can see Bacula apparently wrote 2,058,019,117,056
>>> bytes (approx. 2 TB) but my tape is just 1.5 TB capacity. Does anybody
>>> know why? My job isn't using compression so I really don't understand
>>> this.
>>
>>
>> The job may not be using compression but the tape drive itself may have 
>> compression enabled, which could account for being able to write 2 TB to the 
>> LTO-5 tape.
>>
>> (The 1.5 TB capacity is the native capacity of an LTO-5 tape without 
>> hardware compression enabled.)
>>
>> Cheers,
>>
>> Paul.
>>
>>
>
> Hi, excuse me if I'm a newbie on this but, how and where can I verify
> if hardware compression is enabled? It would be on the web
> administration of my tape library?
>

Hardware compression has to be on to achive this and it is desired. HW
compression will actually speed up your backups since the tape drive
can compress faster than it can write..

John

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