Fedora ARM Secondary Architecture/iSCSI

iSCSI

iSCSI is SCSI (Small Computer System Interface) block device support over Internet (TCP/IP). It's basically a way of doing a storage area network (SAN) using $20/port gigabit ethernet instead of $3000/port FibreChannel connections.

Kernel

To test iSCSI on the OpenRD-Client system, a new kernel was required, with iSCSI support built-in or in modular form:

• Kernel sources: the upstream kernel does not have OpenRD-Client support (though it does support the OpenRD-Base). Patched source obtained from git://repo.or.cz/linux-2.6/linux-2.6-openrd.git -- see discussion at http://groups.google.com/group/openrd/browse_thread/thread/6ec7b4b39700e114
• Cross-compiled on CDOT workstation HongKong using the AM cross-development toolchain available at http://fedora-arm.wantstofly.org/cross/
• Config file used: http://hongkong/chris/openrd-iscsi-kernel/openrd-iscsi-kernel-2.6.33-rc8.config.txt

Results:

• Kernel: http://hongkong/chris/openrd-iscsi-kernel/uImage-2.6.33-rc8
• Modules: http://hongkong/chris/openrd-iscsi-kernel/modules-2.6.33-rc8.tgz

Results

iSCSI seems to work, but only to a point:

• We can login to an initiator (netbsd-iscsi package on HongKong x86_64).
• However, under heavy load (first noticed when creating a mock buildroot cache), the target receives invalid opcodes, causing the connection to fail.
  • Experimenting with a /proc/cpu/alignment value of 3 (fixup+warn) did not clear the issue.
  • Using the exact same target with a F12 x86_64 initiator is successful.