[Stgt-devel] iSER multiple readers

[Robin Humble]

Hi,

I think I'm seeing iSER read corruption problems.
a) in stock centos5.1 when not using kernel 2.6.22.6 I get read
   corruption with just a single reader
b) every kernel/OS/ofed combination that I've tried when there are
   multiple simultaneous readers

the multiple reader problem happens whether the data is read from
multiple luns or clients or... well, just multiple reads to a single
tgtd doing iSER seems to be enough to cause it.

I'm hoping these problems are just something that I've broken in my
setup... previously 2.6.18-52.el5 + centos5 worked (in the single
reader case) but I can't make it work now.

is anyone else seeing easy read corruption?

the easiest way I can reproduce it is:
 initiator side - write data:
   lmdd if=internal of=/dev/sdc opat=1 bs=1M count=1000
 target side - check that the file is ok (it is):
   lmdd of=internal if=/mnt/ramdisk/file ipat=1 bs=1M count=1000 mismatch=1
 initiator side - read and check data (is sometimes ok):
   lmdd of=internal if=/dev/sdc ipat=1 bs=1M count=1000 mismatch=1
 initiator side - read data with 2 processes at once (always fails):
   lmdd of=internal if=/dev/sdc ipat=1 bs=1M count=1000 mismatch=1 &
   lmdd of=internal if=/dev/sdc ipat=1 bs=1M count=1000 mismatch=1 &

I'm using the kernel git tree of stgt.
I don't see any problems when using TCP IPoIB.

cheers,
robin