Re: LTO8 tape profile - amtapetype

You should get substantially faster. That said, throughput to the tape will depend on a lot of 
things about your system and where the bottleneck actually is. The maximum throughput of dual SAS2 
is 6Gbit/s, which would be 750MB/s. So, you aren't likely to come close to the 900MB/s for 
compressible data that LTO8 is rated for. If there are other things going on using the SAS 
bandwidth, like your hard drive systems, then that bites into what's available for pushing out to 
tape. Then there is the cpu for generating the data stream.

I've only gotten up to LTO7. However, it took some tweaking of my supermicro servers to approach the 
rated speed for the LTO7. The tape drives are on a dedicated SAS card. The disk drives are on a 
separate SAS card. My servers have two cpus with I think 16 core each, and 64GB memory. So, even 
though they are doing a lot of other stuff, Amanda can still push the LTO7 approaching its rated speed.


On 9/28/21 5:10 AM, David Simpson wrote:
>
> Just ran amtapetype against an LTO8 tape + HP MSL3040 (with SAS drives). Debian 11.
>
> Some observations:
>
> -compression on, expected
> -length looks ok
>
> -speed .. should I have expected more? Seemed a bit low I thought..
>
> -no LEOM.. I don’t know if it’s the hardware or the Debian 11 kernel or both, though understand 
> this is not essential
>
>
>
> Checking for FSF_AFTER_FILEMARK requirement
>
> Applying heuristic check for compression.
>
> Wrote random (uncompressible) data at 96137551.7377049 bytes/sec
>
> Wrote fixed (compressible) data at 167554018.742857 bytes/sec
>
> Compression: enabled
>
> Writing one file to fill the volume.
>
> Wrote 12011529469952 bytes at 94902 kb/sec
>
> Writing smaller files (120115265536 bytes) to determine filemark.
>
> define tapetype unknown-tapetype {
>
> comment "Created by amtapetype; compression enabled"
>
> length 11730009248 kbytes
>
> filemark 4132 kbytes
>
> speed 94902 kps
>
> blocksize 32 kbytes
>
> }
>
> # LEOM is not supported for this drive and kernel
>
>
>
>
>
> -------------
>
> David Simpson - Senior Systems Engineer
>
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>
> King Edward VII Avenue,
>
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>
> David Simpson - peiriannydd uwch systemau
>
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>
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>
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-- 
---------------

Chris Hoogendyk

-
    O__  ---- Systems Administrator, Retired
   c/ /'_ --- Biology & Geosciences Departments
  (*) \(*) -- 315 Morrill Science Center III
~~~~~~~~~~ - University of Massachusetts, Amherst

<[email protected]>

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Erdös 4