Hello again,
Might I add a few lines I've already added to Rumkos original mail before?:
Spooling is very good, but shouldn't slow down backup since this affects
per-night-capacity.
Also, I thought about simultaneous jobs going on several drives of one
machine at a time:
Could it be done to give each job or each drive a spoolfile on disk that
works on a fifo principle like Rumko mentioned?
So using of multiple drives would be independent from each other's spooling and thus data could be written earlier on some drives while others still spool.
Hope this thing isn't too big!
Best Regards,
Christoff
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Hello,
I am not likely to accept the Feature request as it stands (perhaps after some
changes) for the following two reasons:
1. You mention that this feature will prolong the tape's lifetime, but I see
no impovement in this regard over the current code.
2. Once the spool file fills, it is full. To then restart filling it while it
is despooling seems to me to be rather impossible on the one hand, and would
lead to a lot of race conditions on the other hand. First, despooling
requires reading the spool file and writing it to tape. *Only* when the full
spool file has been read can it be truncated and thus free up space for
additional spooling. Second, if one were somehow to figure out out to
release blocks at the beginning of a file, you would then be in a condition
where you had a lot of excess activity on the computer where the despooling
would be constantanly blocking and deblocking the new FD writes. This would
be *extremely* inefficient.
One possibility in continuing spooling would be to introduce "multiple" spool
directories or some way to partition a spool directory so that it would say
fill half-way and then begin despooling while the other half could continue
spooling.
On Wednesday 21 June 2006 18:31, Rumko wrote:
> Item n: Spooling data while despooling it
> Origin: Rumko <[EMAIL PROTECTED]>
> Date: 21 June 2006
> Status:
>
> What: Currently when fd runs out of data or maximum spool size is
> reached, the sd starts despooling. While it is despooling, the fd does
> not spool the data until all data has been despooled. For performance
> reasons (and it would prolong tape's lifetime), the fd should spool
> data while the data is being despooled by the sd.
>
> Why: Better performance on tape drives (writing would be
> prolonged, because while writing the data, more would be spooled and
> made available to the sd) and longer lifetimes for the tapes.
>
> Notes: I was thinking of 2 solutions. Perhaps a FIFO? But there
> comes a question, (since i dont know much about fifos) how much data
> can be put into a fifo at one time and if theres a limit, what happens
> when you reach it? Will the fd still be able to start piping data into
> the fifo after it has already filled it once? ... The second solution
> would be separate files. Perhaps the sd should inform the fd 5 seconds
> (which should be settable in the config files) before running out of
> data that the fd should start spooling data into a new file and leave
> the old one exclusively to the sd (so that there would be no conflicts
> or any other problem that would fall into this realm).
>
>
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--
Best regards,
Kern
(">
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