Re: LTO8 tape profile - amtapetype

Here's mine:

define tapetype LTO8-compoff {
     comment "Created by amtapetype; compression disabled"
     comment "/usr/sbin/amtapetype -f -b 1024k /dev/nst2"
     length 11732915200 kbytes
     filemark 5006 kbytes
     speed 172710 kps
     blocksize 1024 kbytes
}

It's an FC drive on a Dell ML3 Tape Library.

On 2021-09-28 3:00 p.m., Chris Hoogendyk wrote:
> 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
>>
>> ARCCA, Redwood Building,
>>
>> King Edward VII Avenue,
>>
>> Cardiff, CF10 3NB
>>
>> David Simpson - peiriannydd uwch systemau
>>
>> ARCCA, Adeilad Redwood,
>>
>> King Edward VII Avenue,
>>
>> Caerdydd, CF10 3NB
>>
>> [email protected] <mailto:[email protected]>
>>
>> +44 29208 74657
>>
-- 
Luc Lalonde, analyste
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