Re: [Bacula-users] Volume retention starting time (documentation error?)

[Ivan A. <iad...@ri...>]

Hi Kern,

Well, I am not a native English speaker so I might be wrong interpreting the 
text as I do. This is one reason why I am seeking help posting on the list. I 
think this configuration setting is important enough to make sure the 
documentation is as clear as possible about it.

--Ivan

On Sunday, June 18, 2017 4:10:51 PM EDT Kern Sibbald wrote:
> Hello Ivan,
> 
> You are free to view the text any way you want, but since I wrote it,
> what I see is:
> 
> The problem is that the text does not say when the retention time
> begins.  It only says when the retention period can begin to be applied
> by Bacula.
> 
> Kern
> 
> On 06/18/2017 09:19 PM, Ivan Adzhubey wrote:
> > Hi Kern,
> > 
> > I was referring only to the specific claim that the retention window for
> > volume is counted from the moment of Append->Full/Purged/Used transition
> > of
> > the volume's status. The phrase in section 24.2 which says this is very
> > unequivocal and is also totally wrong. The rest of the pruning process is
> > described correctly, as far as I was able to comprehend it.
> > 
> > --Ivan
> > 
> > On Sunday, June 18, 2017 2:53:56 AM EDT Kern Sibbald wrote:
> >> Hello,
> >> 
> >> I haven't taken a look at the code, so what I say is subject to
> >> confirmation.
> >> 
> >> I believe what is written is basically correct but with a nuance that is
> >> not clearly explained.  What is correct is that the Volume cannot be
> >> recycled until it is in a state other than Append, exactly as described
> >> below.  Consequently, the data will remain on the Volume even if there
> >> are no records in the Catalog that reference it, until the Volume has
> >> been recycled. However, once its records are subject to pruning, they
> >> will be pruned if the retention period measured from the last write time
> >> has expired.
> >> 
> >> Each pruning (File, Job, Volume) is independent, and in addition the
> >> most important one in terms of "data loss" is Volume Retention, so
> >> drawing conclusions for Volume pruning based on pruning for File or Job
> >> records is not likely to work.
> >> 
> >> I will look at the code to ensure that what I am saying is correct then
> >> attempt to improve the documentation ...
> >> 
> >> Best regards,
> >> Kern
> >> 
> >> PS: Note, the algorithm is designed to preserve the data as long as is
> >> possible.  However, there are a few quirks of the current implementation:
> >> 
> >> 1. Assuming you have a Job that writes on a Volume.  That Volume will
> >> not automatically be pruned until the Job is run again.
> >> 
> >> 2. If a Volume is only partially full so it remains in Append state.  As
> >> long as no Jobs write to the Volume to fill it, it will not be
> >> pruned/purged.
> >> 
> >> One of my projects over the next year or two is to implement a new
> >> pruning/recycling algorithm that will be *much* simpler to understand
> >> and easier to calculate  how long the data will be in the Catalog and on
> >> the Volume.
> >> 
> >> On 06/18/2017 12:13 AM, Ivan Adzhubey wrote:
> >>> Hi,
> >>> 
> >>> In section "24.2 Pruning Directives", Bacula documentation claims that
> >>> the
> >>> Volume Retention period begins only *after* the volume has already
> >>> switched to a status other than Append:
> >>> 
> >>> ---quote---
> >>> A key point is that this time period [Volume Retention] is not even
> >>> considered as long at the Volume remains appendable. The Volume
> >>> Retention
> >>> period count down begins only when the Append status has been changed to
> >>> some othe status (Full, Used, Purged, ...).
> >>> ---quote ends---
> >>> 
> >>> I believe this is not true. In the rest of documentation, the three
> >>> independent retention periods (File, Job, and Volume) described as all
> >>> starting at the same point: specifically, at the end run time of a job.
> >>> 
> >>> Thanks,
> >>> Ivan




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