Zitat von Stephen Thompson <stephen AT seismo.berkeley DOT edu>:

> On 09/25/2012 10:43 AM, Alan Brown wrote:
>> On 25/09/12 17:43, Stephen Thompson wrote:
>>> Our Sun/Oracle service engineer claims that our drives do not require
>>> cleaning tapes.  Does that sound legit?
>>
>> In general: true (as in, "Don't do it as a scheduled item"), but all LTO
>> drives require cleaning tapes from time to time and sometimes benefit
>> from loading one even if the "clean" light isn't on. It primarily
>> depends on the cleanliness of the room where the drive is.
>>
>>> Our throughput is pretty reasonable for our hardware -- we do use disk
>>> staging and get something like 60Mb/s to tape.
>>
>> 60Mb/s is _slow_ for LTO3. You need to take a serious look at what
>> you're using as stage disk and consider using a raid0 array of SSDs in
>> order to keep up.
>
>
> Why do you say that's slow when the max speed appears to be 80?
>
> http://en.wikipedia.org/wiki/Linear_Tape-Open
>

The maximum *native* speed with uncompressed data is 80Mb/s. As the  
drives do compression to get more data to the tape the speed to  
deliver data must be higher. If you use the optimistic 2:1 compression  
from marketing your tape drive is actually crawling with 30Mb/s which  
is not even 50% of the native speed.
If you suspekt bacula bug you can still use dd to fill the tape and  
see what you get in speed/capacity.

Regards

Andreas



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