On 4/24/18 7:38 AM, Hannes Reinecke wrote:
On 04/24/2018 02:25 PM, Nicolas D wrote:
Hello everyone,
I tried googling a lot about this problem, but I had no luck till now.
I am having some trouble to read from a dvd/bd drive that is configured
with targetcli with pscsi driver on different not so old linux versions:
- debian (version: saddly don't have the computer with me and don't
remember exactly but should be Jessie)
- ubuntu (14.04/kernel 3.13)
The problem is the same with all the initiator/os I could play with:
- Core-iSCSI/Linux
- MS-initiator/Windows
- StarWind/Windows
- Sns GlobalSan/MacOS
The actual problem is that my target don't react well when the initiator
ask to read more than 16KB in one read instruction: the response is a
sense error or unit error (error discovered in pcap trace, thanks to
wireshark).
I could lower the MaxTransferLength with the "MS-initiator/Windows" and
for that initiator/os it works now perfectly.
https://support.zadarastorage.com/hc/en-us/articles/213024226-Recommended-Windows-iSCSI-initiator-Registry-configuration
But Sns GlobalSan for example does not support limiting read size on is
side, and I think it's definitively the target that has to tell the
initiator about this MaxTransferLength attribute, or I may be wrong?
I tried to tweak some parameters with targetcli, but:
- lowering fabric_max_sectors does not seem to help
- hw_max_sectors=256 hw_block_size=2048 are read-only
I have definitively trouble finding documentation on all other
backend attributes.
I have the impression that my problem is more config related, it's why I
did not took the time to write all exact versions of the os/tools I use.
If you think I am wrong, I'll provide all useful informations.
Thank you for your help and for all the job already made to have this
iscsi stack working in linux.
'pscsi' is the SCSI pass-through, so it'll be presenting the values
from the underlying device; I doubt you can change that.
What you could try is to mount the DVD, and export the mountpoint via
the file backend; that way you should be able to tweak the parameters.
Adding to what Hannes is saying, if you need true dvd/cd emulation you can
use file optical media backstore via user:fbo from tcmu-runner.
Bryant
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