On 12/03/16 00:14, Heitor Faria wrote:
>
>> 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.

If you use tape, you need spooling on (fast) SSD. If you don't need to 
use tape then spooling is superfluous.

Because of the cost of drives, tape is only worth using once you pass 
about 1-200TB or so needing to be backed up (or several hundred small 
systems) and at that point you're going to want multiple simultaneous 
backups anyway.

Don't bother with DAT for backups. It's not reliable due to the narrow 
tape format. Any minor defect in the substrate translates to a major 
loss and in any case it's too small to be worth the hassle in comparison 
to using solid state storage.

Apart from DAT and  LTO/3592/T10000D every other tape format is now 
abandonware so there's not much point in persisting with them and even 
IBM is looking at dropping 3592 in favour of LTO. I wouldn't be at all 
surprised to find Oracle announcing that T10000 format is end of life 
soonish too. The tape market is too small to support 3 competing half 
inch formats even if 3592 and T10000D are twice the capacity of LTO7 
(the cost of cartridges is a lot more than twice as much as LTO7, as are 
the drives, so there's no financial incentive to use them in new 
installations.)

Caveat: BDXL is up to 120GB per disc (quad layer) and  It _may_ be worth 
investigating this format for backups, but bacula doesn't play nicely 
with optical media.

HVD development (6TB per disc) was abandoned in 2008. Ritek demonstrated 
250GB BDXL discs (10 layer) 8 years ago but they've never been marketed. 
Ditto with Pioneer's 400GB BDXL format and the "1TB Blueray" disk is now 
4 years past proposed launch date. What's killed all these "smaller" 
formats is cheap(ish) HDD/SSDs, cloud storage and the likes of Netflix. 
That's despite even BDXL 120GB not being large enough capacity to hold a 
complete 4k video title.





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