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Re: Details on Media Auxiliary Memory in partitioned LTO5+ tapes

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On Sunday, 11 February 2018 12:42:12 UTC+1, Michael Bäuerle  wrote:
> 
> AFAIK all LTO media (back to LTO1) have a builtin MAM.
> Looking at the manuals of 15 year old LTO1/2 drives shows that there
> is MAM support and the READ ATTRIBUTE and WRITE ATTRIBUTE commands
> already present.

That's correct.

> 
> > What I cannot deduct from the T10 standards and SCSI reference
> > manuals, is what attributes to return for any particular partition.
> > Only a few of them are specific to a partition, but the specs claim
> > that the drive returns all attributes (starting with x).
> 
> Just to be sure that we are talking about the same things:
> You want to create/emulate a SCSI target device according to SSC that
> implements the optional READ ATTRIBUTE and WRITE ATTRIBUTE commands
> according to SPC?

Correct as well.

> 
> > Several attributes can be interpreted as belonging to the entire tape
> > (lifetime read/written), but could be per partition as well.
> > Others are clearly per tape (mfg date, serial no).
> 
> Can you tell a bit more about what you want to do. Do you want to
> emulate a specific LTO drive (if yes, which one?) or do you want
> to create a generic tape emulation with support for partitions?

I'm trying to make a fairly generic emulation for LTO, STK T10K and IBM TS11xx drives (and then some others). I am then trying to copy as many attributes from a physical device, and emulate those on my virtual device.

The issue I run into, is with for instance LTFS-formatted tapes. A Read Attribute for the host attribute 0x802h (application version) returns ASCII text "3.0.0", for both partition 0 and partition 1. What I cannot find is if my emulation needs to maintain separate copies for each partition, or that there's some way to mark this attribute as 'global' so one copy shows up in all partitions.

The point is that some attributes do seem to be global. The load counter, tape manufacturer data, tape serial number etc are present in all partitions. Some others appear to be maintained on a per-partition base. I'm trying to be as close as possible to the real thing, but can't figure out if there is a way to tell global attributes apart from per-partition ones.

Thanks,
Rob

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Thread

Details on Media Auxiliary Memory in partitioned LTO5+ tapes scsirob <scsirob@gmail.com> - 2018-02-10 23:36 -0800
  Re: Details on Media Auxiliary Memory in partitioned LTO5+ tapes Michael Bäuerle <michael.baeuerle@gmx.net> - 2018-02-11 11:41 +0000
    Re: Details on Media Auxiliary Memory in partitioned LTO5+ tapes scsirob <scsirob@gmail.com> - 2018-02-28 05:47 -0800
      Re: Details on Media Auxiliary Memory in partitioned LTO5+ tapes Michael Bäuerle <michael.baeuerle@gmx.net> - 2018-03-04 11:25 +0000
        Re: Details on Media Auxiliary Memory in partitioned LTO5+ tapes scsirob <scsirob@gmail.com> - 2018-03-12 02:03 -0700

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