So, that is the data transfer rate measured before the compressor?
We used 3:1 or 4:1 as our assumed average compression ratio. 360
MB/sec before the compressor at 4:1 compression would mean that the
write rate at the head would be about 90 MB/sec? Is that about
right? If so, then the data transfer rate would be between about 90
MB/s and 360 MB/s depending on the compressibility of the data.
1 TB written at 360 MB/s comes out to about 8 hours (if I did the
math correctly). At 90 MB/s, it would be about 32 hours.
DaveD
On 11/1/2017 3:50 PM, Paul Berger
phb.hfx@... [hp_agilent_equipment] wrote:
???
The theoretical write speed is 360 MB/s??? at maximium
compression, however in the real world mileage will vary.???
That also depends on being able to keep data streaming out
to the device.??? Block size can also impact the throughput.
Paul.
On 2017-11-01 6:42 PM, Tony
Goodhew
tony_goodhew@...
[hp_agilent_equipment] wrote:
???
Hey Dave,
???
How long does it take to push 1TB
to these LTO devices? I was just starting to look at
them last weekend but I couldn???t find anything
definitive ??? It seemed that people were saying
!500GB an hour.
???
Any insights?
???
Thanks,
TonyG
???
Sent from for Windows 10
???
???
On 11/01/2017 04:56 PM, Dave Daniel kc0wjn@...
[hp_agilent_equipment] wrote:
> You can also look at DLT tape drives. I
haven't worked on
> non-IBM-mainframe tape for many years, so I
haven't kept track of either
> DLT or LTO. I believe LTO is in it's 8th
generation now. I believe,
> though, that LTO has surpassed DLT in terms
of capacity and performance,
> probably also in terms of reliability.
>
> Maybe someone out there has more current
knowledge.
LTO-8 was just announced; I don't know if it's
shipping yet. Those
are hugely capacious tapes.
DLT topped out at 40/80GB, then gave way to SDLT.
SDLT topped out at
300/600GB. There were a few variants like the
DLT-S4 (800GB) and the VS
series (80/160GB), but I never saw many of those
around.
For cost-sensitive home archival use, SDLT-II
media in an SDLT-600
drive (300GB native/~600GB compressed) is probably
the sweet spot. LTO
media is still pretty expensive in any volume.
Many organizations have a "use once" policy for
tapes, and modern
tapes are quite robust. Lots of people take them
home from work and
liquidate them in batches on eBay. They've
typically been used once,
and are barely broken in. They are usually pretty
trustworthy.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
