SAS resource locations

Many hardware error logs identify the location of a physical device, such as a SAS disk, using what is called a resource location (or simply resource).

SAS resource locations for PCI-X and PCIe controllers, except CCIN 57CD

The resource format is: 00cceell where:

cc identifies the controller's port to which the device, or device enclosure, is attached.
ee is the expander's port to which the device is attached. When a device is not connected to a SAS expander, for example, the device is directly connected, the expander port is set to zero.
Typically, the expander port will be in a range of 00 to 3F hex. A value greater than 3F indicates there are two expanders (for example, cascaded expanders) between the controller and device. For example, a device connected through a single expander might show an expander port of 1A, while a device connected through a cascaded expander might show an expander port of 5A (that is, a value of 40 hex added to the expander port indicates the presence of a cascaded expander), but in both cases, the device is connected off port 1A of the expander.

A value of FF indicates the expander port is not known.
ll is the logical unit number (LUN) of the device.
A value of FF indicates the LUN is not known.

The resource location is also used to identify a disk array. For a disk array, the resource format is: 00FFnn00 where:

nn is the controller disk array identifier.

A resource can identify a physical device, a disk array, or it can identify other SAS components. For example:

00FFFFFF indicates the identity of the device is not known.
00ccFFFF identifies only a controller's SAS port.
00cceell identifies the controller port, expander port, and LUN of an attached device.
00FE0000 indicates a remote SAS initiator
00FFnn00 indicates a disk array
FFFFFFFF indicates a SAS RAID controller.

Figure 1. Example SAS subsystem resource locations Example of SAS subsystem resource locations

SAS resource locations for PCIe controller 57CD

The following figure depicts the resource locations for the CCIN 57CD PCIe SAS RAID and SSD Adapter. Each of the integrated SSDs is directly connected, and thus the expander port is equal to 0 in the resource. The LUN of each device is also zero.

Figure 2. SAS resource locations for CCIN 57CD PCIe SAS RAID and 3 Gb x8 SSD Adapter

SAS resource locations for PCIe2 or PCIe3 controllers

The resource format is: ttcceess where:

tt identifies the type of device.
Note: A value of 00 indicates the device is a physical device (HDD or SSD). A value other than 00 indicates the device is a logical device or a SAS RAID controller.
cc identifies the controller's port to which the device, or device enclosure, is attached.
ee is the expander's port to which the device, or cascaded expander, is attached. When a device is not connected to a SAS expander, for example, the device is directly connected, the expander port is set to FF.
A value of FF indicates the expander port is not known or no expander exists.
ss is the cascaded expander’s port to which the device is attached.
A value of FF indicates the cascaded expander port is not known or no cascaded expander exists.

The resource location is also used to identify a disk array. For a disk array, the resource format is: FCnn00FF where:

nn is the controller disk array identifier.

A resource can identify a physical device, a disk array, or it can identify other SAS components. For example:

00FFFFFF indicates the identity of the device is not known.
00ccFFFF identifies only a controller's SAS port or a directly attached device.
00cceeFF identifies the controller port and expander port of an attached device.
00cceess identifies the controller port, expander port, and cascaded expander port of an attached device.
FB0000FF indicates a remote SAS initiator
FCnn00FF indicates a disk array
FFFFFFFF indicates a SAS RAID controller.

Note: In most places (such as the SMIT screens) only the top 4 bytes of the Resource field is shown. However, in some error logs the Resource is identified with an 8 byte value. The ending 4 bytes are always FFFFFFFF and can be ignored in all supported configurations.

For example, the resource identified in the following snippet from an error log would be resource 000608FF.

DISK INFORMATION Resource Vendor Product S/N World Wide ID 000608FFFFFFFFFF IBM SG9XCA2E 50B00460 500051610000FC6C0000000000000000

Figure 3. Example PCIe2 or PCIe3 SAS subsystem resource locations Example PCIe2 SAS subsystem resource locations

Last updated: Wed, May 24, 2017