schrieb Adrian Reyer am 10.07.2011 15:58 (localtime):
...
> I found using Spool Data for copy jobs to be faster for my setup. I have
> fast local disks for spooling, but some of my disk storage is accessed
> vie iSCSI on 1-GBit/s-links.
> However, I am currently running a few copy jobs and the limiting factor
> seems to be my bacula-sd consuming 1 complete CPU, throttling me at
> 55MB/s. The CPU is an older 'AMD Athlon(tm) 64 X2 Dual Core Processor
> 3800+'
Hmmm, interesting point. Is the storage daemon single threaded? I'll
check this, since I have an "old" dual core Xeon, but I checked that
there were at least 25% idle of CPU time (ZFS compression is used, so
that client-to-disk backup is uncompressed avoiding interference with
later (migration) tape drive compression)
>> Maybe this was not an issue with slower tape drives. LTO2 would only
>> suffer from about 6% performance loss, if my wild guess has any truth...
>
> LTO4 as well here, and no ear next to the drive. However, 'mt status'
> won't run as the drive is in use by the copy jobs, how you got that
> info?
On FreeBSD there's a special control device for every sequential access
device (/dev/sa0 /dev/sa0.ctl for example).
No luck so far finding technical end-user-details for the design of LTO
drives. I'm really wondering if file marks are written to the tape or
just in the cartridge memory chip. And even if they get written to the
tape, is it unavoidable that streaming is interrupted???
Questions over questions, hopefully one magneto-guru will read...
Thanks,
-Harry
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