Re: [Bacula-users] Copy disk to tape is 4x slower than tar

On 11/03/16 20:14, Simon Templar wrote:
In my case using spooling didn’t prevent shoe-shining; it just introduced long pauses while data was spooled. I think all this means is that I can read from my data sources faster than my tape can write.

Unless you are using DAT, do not use mechanical drives for spooling - they can't keep up with the tape drive unless you're using one that's dedicated and only spooling/despooling for a single job (LTO1-2-3, incompressible data) or can't keep up at all (As above with any form of compressible data, or LTO4,5,6,7)

Hello Alan: I have the same perception.

SSD is the only way to fly. After having tested with a PCIe NVMe drive, I'd say that's preferred, but a _fast_ SATA2/3 or SAS2 drive will work too (The old spool was a stripe of Intel SLC SSDs, the new one is a DC3700 card)

I never got this spooling / disk backup fetish. I mean: it keeps data interleaving to happen, but at what cost?

With SSD you can have a ridiculous hight throughput, but you still need to wait backup data being copied to tapes / definitive slow disk. Unless you have a really short backup window at client size, it is useless.

Spooling really comes into its own when you're running multiple jobs. Whilst one job is despooling, others can be spooling. The interleaving effect means all your jobs complete in a faster period of time.

Again I agree with you here. You will tend to have more optimum spooling usage in this scenario if you have enough spooling size.

Regards,

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