f.staedler AT dafuer DOT de wrote (2013/01/02):
> thanks for your quick answer. So the sound of the drive like starting
> and stopping in about 10 second intervals are normal?
Hi, no, it is not normal. Except that you have too small Maximum File Size
setting. I have 8 GB, which means atleast one file per one minute, and it
can sustain ~ 140 MB/s over the whole file. Furthermore, I have increased
Maximum File Size to 16 GB right now and I'm thinking even about 32 GB.
> While writing this - is maybe Maximum File Size of SD the reason? Since
> transferred data is about 1GB and it is writing an EOF mark to tape? If
Almost certainly yes. I have ~ 4-8 seconds pauses for each EOF mark like
you, so it means, that 1 GB is too small value, because it is written
in ~ 7 seconds and you have almost 50 % overhead.
> so, a full tape will have about 1500 EOF marks - can I safely put it to
> a higher value? As far as I understand the only drawback are maybe
> slower restores of files. But I don't think that would be a problem,
> since new data arrive in 5-10GB chunks.
If you have disk spooling and tape file seeks (but I think that bacula can
do even record seeks), then average delay for two minute files (Maximum
File Size = 16gb) is just about one minute per random seek, which I have
usually just one per one restore. And if you count tape loads and unloads
plus robotics and regular tape seeks (again typical times around one
minute each), then impact of Maximum File Size = 16gb (or even more) for
restores is not so significant.
Furthermore, I had problems with read performance atleast 80 MB/s for
LTO-3 and now even atleast 140 MB/s for LTO-5 from conventional HW RAID0
with mechanical disks, when there were another faster spooling and
writing jobs, so I decided to switch to HW RAID0 with SSDs.
Best regards.
--
Rudolf Cejka <cejkar at fit.vutbr.cz> http://www.fit.vutbr.cz/~cejkar
Brno University of Technology, Faculty of Information Technology
Bozetechova 2, 612 66 Brno, Czech Republic
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