Re: lsscsi and sg3_utils betas for testing 64 bit LUNs

[Douglas Gilbert <dgilbert@interlog.com>]

On 13-03-06 10:10 AM, Douglas Gilbert wrote:
> To facilitate testing Linux 64 bit LUNs (the kernel holds
> only 32 bit LUNs internally at the moment), I have put up
> beta versions of lsscsi and the sg3_utils packages, see the
> top of this page: http://sg.danny.cz/sg/
>
> lsscsi version 0.27 (beta 1) adds a --lunhex (-x) option,
> here is an example of its use:
>
> # lsscsi -gs

Last second edits; the invocation line should be 'lsscsi -g'

> [0:0:0:0]    disk    ATA      INTEL SSDSC2CW12 400i  /dev/sda   /dev/sg0
> [7:0:0:1]    disk    Linux    scsi_debug       0004  /dev/sdb   /dev/sg1
> [7:0:0:49409]wlun    Linux    scsi_debug       0004  -          /dev/sg2
>
> # lsscsi -g --lunhex

And the invocation here should be 'lsscsi --lunhex'
What is happening is that redundant zeros to the right
(according to the T10 LUN definition) of the LUN are dropped
to lessen the clutter. When --lunhex is used twice (or -xx)
then the whole 16 hex digits are output:

> [0:0:0:0x0000]              disk    ATA      INTEL SSDSC2CW12 400i  /dev/sda
> [7:0:0:0x0001]              disk    Linux    scsi_debug       0004  /dev/sdb
> [7:0:0:0xc101]              wlun    Linux    scsi_debug       0004  -
>
> # lsscsi -xx
> [0:0:0:0x0000000000000000]  disk    ATA      INTEL SSDSC2CW12 400i  /dev/sda
> [7:0:0:0x0001000000000000]  disk    Linux    scsi_debug       0004  /dev/sdb
> [7:0:0:0xc101000000000000]  wlun    Linux    scsi_debug       0004  -
>
> Additionally if sysfs offers a 64 bit (unsigned) integer in decimal
> for a LUN then this version will use it (previous lsscsi versions
> would have truncated the LUN to 32 bits).
>
>
> In the sg3_utils beta the sg_luns utility is expanded to better
> handle T10 (SAM-5) LUNs and represent them in Linux 'word
> flipped' form if requested. sg_luns has an additional
> --test=LUNHEX option that can be used for decoding arbitrary
> T10 LUNs, for example:
> # sg_luns --test=020304aa01bb00ff
> Decoded LUN:
>    Peripheral device addressing: bus_id=2, target=3
>    >>Second level addressing:
>      Peripheral device addressing: bus_id=4, target=170
>    >>Third level addressing:
>      Peripheral device addressing: bus_id=1, target=187
>    >>Fourth level addressing:
>      Peripheral device addressing: lun=255
>
> # sg_luns --test=020304aa01bb00ff -H
> Decoded LUN:
>    Peripheral device addressing: bus_id=0x02, target=0x03
>    >>Second level addressing:
>      Peripheral device addressing: bus_id=0x04, target=0xaa
>    >>Third level addressing:
>      Peripheral device addressing: bus_id=0x01, target=0xbb
>    >>Fourth level addressing:
>      Peripheral device addressing: lun=0xff
>

The trailing "L" on that hex number requests the Linux
LUN representation. And if -H was given twice the
Linux word flipped integer would be 0x00ff01bb04aa0203 .

> # sg_luns --test=020304aa01bb00ffL -H
> Linux 'word flipped' integer LUN representation: 0xff01bb04aa0203
> Decoded LUN:
>    Peripheral device addressing: bus_id=0x02, target=0x03
>    >>Second level addressing:
>      Peripheral device addressing: bus_id=0x04, target=0xaa
>    >>Third level addressing:
>      Peripheral device addressing: bus_id=0x01, target=0xbb
>    >>Fourth level addressing:
>      Peripheral device addressing: lun=0xff
>
>
> Now I'm hoping Hannes Reinecke will issue a new set of the
> "scsi: 64-bit LUN support" patches that address the issues
> that have been brought up. Then the real testing can begin.


And finally a question, if a target had a lot of LUNs
then the sorting order will help finding one in a long
list. So what sorting order should 64 bit LUNs have?

Doug Gilbert