Steven Hammond


On 6/2/2017 8:28 AM, Kern Sibbald wrote:

Hello,

See below ...



On 06/02/2017 01:44 PM, Richard Fox wrote:

Hi,

On Fri, Jun 02, 2017 at 01:24:46PM +0200, Kern Sibbald wrote:

I don't seem to have the original post of Richard Fox, so could you please

specify what "this directive" is in the sentence:

Otherwise, this advice is a little contradictory to the documentation which states "On most modern tape drives, you will not need to specify this directive.

My apologies, I had sent the message from the wrong address and
cancelled moderation on it. I was hoping nobody would notice.

My original message asked if this discussion was in regard to the
"Maximum block size" (and presumably "Minimum block size") from the
device resource.

"Are you both referring to "Maximum block size" (and presumably "Minimum block size") from the

Device resource?

As for me: Yes.

If not please ignore the rest of this message. Otherwise, this advice is a little contradictory to the documentation which states "On most modern tape drives, you will not need to specify this

directive.".

Yes, this is completely correct. If you really want to squeeze every ounce of performance in writing drives, you might want to increase the Maximum Block Size.

More importantly however, the documentation (for Bacula 7.2 anyways) says: "The maximum size-in-bytes possible is 2,000,000." which contradicts the assertion that these can be specified

as 2MB which is not the same thing. Is the documentation inaccurate on
this subject?"

Unless I am missing something, in Bacula 1000000 and 1 MB are the same thing. In Bacula 2 M is 1048576 bytes. This may be a bit confusing, but it is historic.

Best regards,
Kern

On 06/01/2017 02:51 PM, Cejka Rudolf wrote:

Richard Fox wrote (2017/06/01):

Otherwise, this advice is a little contradictory to the documentation which states "On most modern tape drives, you will not need to specify this directive.".

Given that Linux with LTO-X tape drive is probably a majority system here (not counting configurations without tape drives), the statement is slightly misleading. I'm convinced that it is really not needed because of tape drive, server nor HBA, but it seems that it is really needed because of Linux. However it is not a real problem, because Linux allows to increase the block size "naturally", with the exception that you have limiting HBA.

More importantly however, the documentation (for Bacula 7.2 anyways) says: "The maximum size-in-bytes possible is 2,000,000." which contradicts the assertion that these can be specified as 2MB which is not the same thing. Is the documentation inaccurate on this subject?

I wrote 2 MB as a general recommendation over various manufacturers and software developers, with non-written suggested value 256 KB or 512 KB as max., so please

take my 2 MB limit just loosely :o)

Thanks,
Rich.

------------------------------------------------------------------------------

Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Bacula-users mailing list
Bacula-users AT lists.sourceforge DOT net
https://lists.sourceforge.net/lists/listinfo/bacula-users

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Bacula-users mailing list
Bacula-users AT lists.sourceforge DOT net
https://lists.sourceforge.net/lists/listinfo/bacula-users