iscsi (initiator) unstable

[Zafer Aydoğan <zafer%aydogan.de@localhost>]

Hello List,

I am new to the iscsi world and I am experiencing some difficulties getting
iscsi to work reliably with NetBSD without knowing the core reason.
I hope to figure it out and to fix the issues with this discussion.

Status Quo:
I have a server running 6.99.45 amd64 very smoothly and I have an
iscsi target in
the same network that I can connect to as described in iscsictl(8).

After the logging in the sd0 disk device is present (or dk0 when
formatted with gpt)
and I can successfully newfs and mount the disk.

Everything looks fine to this point.

But the trouble starts as soon as I am writing data to the new storage.

Copying files or creating a big sparse file (50 GB) with dd will stop
the connection
to the storage quite fast. Disk activity with small files will delay
the interruption. The smaller the later.
There is no obvious network problem. I can see packets flying around
until they suddenly stop.
When the connection stops, then the process is in state tstile (ps D).

Everything else works fine. No crash or hang.
I can cd to /storage but writes to the disk will not complete and
wedge in tstile as well.
Additionally, I can re-establish the iscsi session, which will give me
a new disk device sd1, that I can mount and the story starts over.
Running iscsid in debug mode does not reveal anything special.

I tried different mount options (sync, log) because I thought
that syncing data to the disk was the reason. But no luck.

In my frustration I tried different file systems (lfs, ext2fs, v7fs),
but all of them will stop working sooner or later, except v7fs, but
thats due to the very low write-speed, I think.

Any help is appreciated.

Cheers,
Zafer