The following applies to latest 'Development stream', currently based on kernel 3.11.
OSA, HiperSockets, QETH
Networking - OSA - Layer 3 mode only
The following applies only when running in Layer 3 mode (i.e. not in Layer 2 mode):
Networking - OSA - Layer 2 / Layer 3 traffic
The following restriction on Layer 2 and Layer 3 traffic applies only when running in Layer 2 mode on early IBM System z9:
The above restriction does not apply when running on recent z9 or newer System z.
Networking - HiperSockets - No Layer 2 / Layer 3 traffic
Large MTU sizes may fail due to "order-N allocation failed" problem
- Please see http://www.ibm.com/systems/z/connectivity/products/fc.html for FCP channel limitations.
- If access to a device is lost although it is currently mounted, a limitation of the kernel 2.6 code may be triggered which causes the kernel to hang or to crash. It is recommended to use a multi-pathing setup.
- Error recovery by the Linux SCSI stack on a (virtual) FCP adapter may impact ongoing SCSI traffic to other devices attached to the same adapter. Therefore, it is recommended to use a unique (virtual) FCP adapter (unique device number, see 'lscss' in s390-tools ) to isolate a device from other SAN traffic. In particular, this applies to tape devices.
- In case of non-recoverable errors (e.g., temporary adapter failure, low-level data loss on the fiber), zfcp uses the host return codes ("host_byte") provided by the Linux SCSI stack (see include/scsi/scsi.h ) to indicate these error conditions to upper layer drivers. In particular, low-level errors can be disruptive to the SCSI traffic of devices which do not allow retries (e.g., tape read/write commands). It is recommended to the upper layer driver to try to recover these conditions, or just to return I/O error to the application. In case of a high frequency of host return codes, please check your SAN equipment (firmware etc.).
- For the dump on panic feature for SCSI disks in a z9 LPAR, MCL G40954.002 in Driver D67L Bundle 18 is required. (z10 has no specific prerequisite)
- FCP-attached IBM tape devices using the IBMtape device driver must be attached through a switch.
- Support for "FCP hardware data router":
- Support for "Support for end-to-end data consistency checking (T10-DIF)":