Displaying information about SCSI devices

For each SCSI device, there is a number of read-only attributes in sysfs that provide information for the device.

About this task

Table 1 summarizes the read-only attributes for manually configured FCP LUNs, including those attributes that indicate whether the device access is restricted by access control software on the FCP channel. These attributes can be found in the zfcp branch of sysfs. The path has the form:

/sys/bus/ccw/drivers/zfcp/<device_bus_id>/<wwpn>/<fcp_lun>/<attribute>

Table 1. Attributes of manually configured FCP LUNs with device access information
Attribute	Explanation
access_denied	Flag that indicates whether access to the device is restricted by the FCP channel. The value is `1` if access is denied and `0` if access is permitted. If access is denied to your Linux instance, confirm that your SCSI devices are configured as intended. Also, be sure that you really want to share a SCSI device. For shared access to a SCSI device, preferably use NPIV). You might also use different FCP channels or target ports.
access_shared	This attribute is obsolete. The value is always `0`.
access_readonly	This attribute is obsolete. The value is always `0`.
in_recovery	Shows if unit is in recovery (0 or 1)

Table 2 lists further read-only attributes with information about the SCSI device. These attributes can be found in the SCSI branch of sysfs. The path has the form:

/sys/class/scsi_device/<device_name>/device/<attribute>

Table 2. SCSI device class attributes
Attribute	Explanation
device_blocked	Flag that indicates whether the device is in blocked state (0 or 1).
iocounterbits	The number of bits used for I/O counters.
iodone_cnt	The number of completed or rejected SCSI commands.
ioerr_cnt	The number of SCSI commands that completed with an error.
iorequest_cnt	The number of issued SCSI commands.
queue_type	The type of queue for the SCSI device. The value can be one of the following types: none simple ordered
model	The model of the SCSI device, received from inquiry data.
rev	The revision of the SCSI device, received from inquiry data.
scsi_level	The SCSI revision level, received from inquiry data.
type	The type of the SCSI device, received from inquiry data.
vendor	The vendor of the SCSI device, received from inquiry data.
fcp_lun	The LUN of the SCSI device in 64-bit format.
hba_id	The bus ID of the SCSI device.
wwpn	The WWPN of the remote port.
zfcp_access_denied	Flag that indicates whether access to the device is restricted by the FCP channel. The value is `1` if access is denied and `0` if access is permitted. If access is denied to your Linux instance, confirm that your SCSI devices are configured as intended. Also, be sure that you really want to share a SCSI device. For shared access to a SCSI device, preferably use NPIV). You might also use different FCP channels or target ports.
zfcp_in_recovery	Shows if unit is in recovery (0 or 1).

Procedure

Issue a command of this form to read an attribute of a manually configured FCP LUN:

# cat /sys/bus/ccw/drivers/zfcp/<device_bus_id>/<wwpn>/<fcp_lun>/<attribute>

where:

<device_bus_id>: specifies the FCP device.
<wwpn>: is the WWPN of the target port.
<fcp_lun>: is the FCP LUN of the SCSI device.
<attribute>: is one of the attributes in Table 1.

Use the lszfcp command to display information about the associated SCSI device.

Alternatively, you can use sysfs to read the information. To read attributes of the associated SCSI device, use a command of this form:

# cat /sys/class/scsi_device/<device_name>/device/<attribute>

where:

<device_name>: is the name of the associated SCSI device.
<attribute>: is one of the attributes in Table 2.

Tip: For SCSI tape devices, you can display a summary of this information by using the lstape command.

Examples

In this example, information is displayed for a manually configured FCP LUN with LUN 0x4010403200000000 that is accessed through a target port with WWPN 0x500507630300c562 and is attached through an FCP device 0.0.3d0c. For the device, access is permitted.
```
# cat /sys/bus/ccw/drivers/zfcp/0.0.3d0c/0x500507630300c562/0x4010403200000000/access_denied
0
```
For the device to be accessible, the access_denied attribute of the target port, 0x500507630300c562, must also be 0 (see Displaying port information).

You can use lszfcp to display attributes of a SCSI device:

# lszfcp -l 0x4010403200000000 -a
0.0.3d0c/0x500507630300c562/0x4010403200000000 0:0:0:0
Class = "scsi_device"
    ...
    device_blocked      = "0"
    ...
    fcp_lun             = "0x4010403200000000"
    hba_id              = "0.0.3d0c"
    iocounterbits       = "32"
    iodone_cnt          = "0xbe"
    ioerr_cnt           = "0x2"
    iorequest_cnt       = "0xbe"
    ...
    model               = "2107900"
    queue_depth         = "32"
    queue_ramp_up_period = "120000"
    queue_type          = "simple"
    ...
    rev                 = ".166"
    scsi_level          = "6"
    state               = "running"
    timeout             = "30"
    type                = "0"
    uevent              = "DEVTYPE=scsi_device"
    vendor              = "IBM"
    ...
    wwpn                = "0x500507630300c562"
    zfcp_access_denied  = "0"
    zfcp_failed         = "0"
    zfcp_in_recovery    = "0"
    zfcp_status         = "0x54000000"