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How to parse the host HBA in the Linux/Unix system can not find LUN path display errors and LUN-related errors, I believe that many inexperienced people do not know what to do about this, so this paper summarizes the causes and solutions of the problem, through this article I hope you can solve this problem.

There are several common SCSI failures in Linux/Unix system, such as: host HBA can not find LUN, path display error, the same LUN shows duplicate LUN ID, failover problem, rescan disk problem, etc., and lists the relevant solutions. Question1: how to dynamically discover a new LUNs in Linux through iSCSI? Platform: RedHat Linux, SuSE Linux problem description: unable to dynamically discover new disk devices root cause: iSCSI...

There are several common SCSI failures in Linux/Unix system, such as host HBA can not find LUN, path display error, the same LUN shows duplicate LUN ID, failover problem, rescan disk problem, etc., and lists the relevant solutions.

Question1: how to dynamically discover a new LUNs in Linux through iSCSI?

Platform: Red Hat Linux, SuSE Linux

Problem description: unable to dynamically discover new disk devices

Root cause:

The iSCSI driver can dynamically discover the target storage system on the Ethernet, however, it cannot dynamically discover the LUN on the storage system. The SCSI middle tier of the Linux operating system is responsible for discovering LUN. Therefore, with Fibre Channel, the user must rescan the SCSI bus to find the newly added LUN, which can be done by restarting the server or reloading the iSCSI module.

Solution:

Root permissions use the following command to reload the iSCSI driver on RHEL 3, RHEL4, SLES 8, SLES 9, Asianux 1.0, and Asianux 2.0:

# / etc/init.d/iscsi restart

Use the following command as root on RHEL5 and SLES 10:

RHEL5:

# / etc/init.d/iscsid restart

SLES 10:

# / etc/init.d/open-iscsi restart

Or

# / sbin/iscsiadm-m session-R

Does the question 2:Linux require LUN 0?

Platform: Linux

Problem description:

1. / proc/scsi/scsi each path contains only one DGC LUN Z.

2. / proc/scsi/qla2?00/ [0-9] shows all LUN except LUN 0, and the asterisk indicates that there is no SCSI registration.

3. Emulex HBA is registered with FA but there is no device entry in / proc/scsi/scsi.

Root cause:

The Linux 2.4.x kernel uses the SCSI INQUIRY command on LUN 0 to determine what type of disk device the system is connected to. Without the LUN 0QLogic and Emulex drivers, an error will be returned instead of issuing an INQUIRY command to the disk device, so the Linux system will not be able to scan the disk device automatically. LUN must be activated manually.

Solution:

This issue can be resolved in the following ways:

1. Map a Gatekeeper to LUN 0. Linux 2.4 is limited by the maximum number of SCSI disk devices, so you may need to specify HLU manually.

two。 Scan the LUN manually. Users should plan the scanning time carefully.

3. Patch the Linux SCSI driver (not recommended).

Please see Primus Solution emc115253 for details.

Problem 3:Linux host Emulex HBA cannot see the disk device

Platform: Linux Kernel 2.4

Problem description:

1. The host cannot see any disk devices after registering and registering on the storage side.

two。 All lpfc driver instance files (for example: / proc/scsi/lpfc/*) cannot see the storage WWN.

Solution:

Follow these steps:

1. Check which modules depend on lpfc with the following command:

Lsmod | grep lpfc

Lpfc 243664 0 [lpfcdfc]

The boldface part of the command output is the module that is using lpfc. Lpfc cannot be deleted until lpfcdfc is deleted.

two。 Use the rmmod command to delete the relevant modules in the following format:

Rmmod lpfcdfc

When the command executes successfully, verify that the module has been deleted by the lsmod command.

3. Use the following command to remove the lpfc module:

Rmmod lpfc

4. Reload the lpfc module using the following command:

Modprobe lpfc

5. After the module is successfully loaded, the PLOGI and storage port information will be initialized, which will be seen in the driver instance file.

It will also scan disk devices automatically. If not, run the command echo'--- > / proc/scsi/scsi to scan disk devices.

Question 4: "powermt display dev=all" Device (s) not found ""

Platform: HP-UX, IBM AIX, Red Hat Linux, UNIX

Software: PowerPath 5.0,

Problem description: unable to view new SCSI disk devices using the command powermt display dev=all

Solution: check the emcgrab log "powermt display options" file to see if the PowerPath array status is set to "managed", or run the command powermt display options on the host.

If you specify that the array is set to "unmanaged", enter the following command:

Powermt manage class=symm (or class=clariion, etc.)

Powermt display dev=all

Powermt save .

Problem 5:Linux host found duplicate LUN ID in proc/scsi/scsi

Platform: Red Hat Linux 5.3

Products: Symmetirx DMX-4, VMAX series

Problem description:

One disk device is presented to two HBA, and two instances are displayed through two different LUN ID on each HBA. The host should see the same instance (LUN 16 instead of 16 and 17) on each HBA instead of two different LUN ID.

Host: scsi5 Channel: 00 Id: 02 Lun: 16

Vendor: EMC Model: SYMMETRIX Rev: 5772

Type: Direct-Access ANSI SCSI revision: 02

Host: scsi5 Channel: 00 Id: 02 Lun: 17

Vendor: EMC Model: SYMMETRIX Rev: 5772

Type: Direct-Access ANSI SCSI revision: 02

Host: scsi3 Channel: 00 Id: 02 Lun: 16

Vendor: EMC Model: SYMMETRIX Rev: 5772

Type: Direct-Access ANSI SCSI revision: 02

Host: scsi3 Channel: 00 Id: 02 Lun: 17

Vendor: EMC Model: SYMMETRIX Rev: 5772

Type: Direct-Access ANSI SCSI revision: 02

Solution:

Check to see if the SPC 2 and SCSI 3 tags are missing. Re-tagging will resolve this issue, and the host must restart for the changes to take effect. Set the flag at the HBA level, for example: symmask-sid 308-dir 8C-p 0-wwn 10000000c99338ca set hba_flags on SPC2,SC3-enable.

When the disk device is set up with SPC 2 and SCSI 3, proc/scsi/scsi will return the correct LUN ID.

Question: can the 6:Linux operating system rescan disk devices without reloading the Linux driver?

Platform: Red Hat Linux,SuSE Linux Enterprise Server (SLES), QLogic

Problem description: after the new LUN is added to the storage array, the device cannot be seen through the operating system's QLogic HBA driver. Restarting or reloading the driver can cause production disruption.

Solution:

Follow these steps to force the driver to rescan the target device, allowing new disk devices to be added. This step triggers the driver to initialize the LUN discovery process. Scan order: first drive layer (qla2300/qla2200, etc.), then Linux SCSI middle layer (i.e. OS scan).

1. 1. Force the scan from the command line and enter the following command:

# echo "scsi-qlascan" > / proc/scsi//

Qla2100, qla2200, qla2300 (2.4kernel driver) or qla2xxx (2.6kernel driver) is the HBA instance number.

2. 2. After performing step 1, use the following command to force the SCSI middle tier to perform a scan and add device table entry for the newly added disk device.

# echo "scsi add-single-device 0 1 2 3" > / proc/scsi/scsi

"0123" is the "host channel LUN".

Problem 7:Red Hat Linux received SCSI error return value 0x20000

Platform: Red Hat Enterprise Linux 4 U2 and above, QLogic,PowerPath

Problem description:

1. 1. Red Hat Linux received the SCSI error return value 0x20000.

2. Kernel: SCSI error: return code = 0x20000

Kernel: end_request: I/O error, dev sdik, sector 4069594

Root cause:

When a port is disabled, unplugged, or reset a fibre Channel switch usually results in a RSCN (Registered State Change Notification) event that is seen by all HBA still connected to the switch. Without warning, multipath software (PowerPath, DMP, MPIO) will not be able to judge.

Note: the return value 0x20000 indicates DID_BUS_BUSY. Not all 0x20000 errors are caused by the RSCN event. A Fabric or array failure can also cause the error. Users should not assume that RSCN must be the cause of the error.

Solution:

To interpret the RSCN event correctly, add a kernel option to the modprobe.conf file. You need to restart for the changes to take effect.

1. 1. Edit / etc/modprobe.conf and add the following line:

Options qla2xxx ql2xprocessrscn=1

2. 2. Save the file.

3. 3. Recompile initrd.

Mkinitrd-f / boot/initrd- `uname-r`.img `uname-r`

4. Restart the system for the changes to take effect.

The problem 8:Linux host can only see one path to connect to storage in / proc/scsi/scsi

Platform: SLES 9 Magi SLES 10 Magi QLogic 8.01.06.01 PowerPath 5.0.1

Problem description:

1. SuSE Linux sees only one path in / proc/scsi/scsi to connect to the storage.

2. PowerPath shows only one path connected to the emcpower device.

3. Even if four paths are configured, / proc/scsi/scsi shows only one path connected to the disk device

Attached devices:

Host: scsi0 Channel: 00 Id: 00 Lun: 00

Vendor: DGC Model: RAID 5 Rev: 0324

Type: Direct-Access ANSI SCSI revision: 04

Powermt display dev=all displays only one path to the emcpower device:

Pseudo name=emcpowera

CLARiiON ID=CK200072300649 [SG_LINUXTST01]

Logical device ID=60060160128C1D00D8D768A3915BDC11 [fiscuat2 DATA]

State=alive; policy=BasicFailover; priority=0; queued-IOs=0

Owner: default=SP B, current=SP B

=

-Host-Stor-I take O Path-Stats--

# HW Path I/O Paths Interf. Mode State Q-IOs Errors

=

0 qla2xxx sda SP B0 active alive 0 0

Root cause:

If the user blocks the PowerPath from displaying the port on the switch to which the HBA0 is connected, the path will fail over. PowerPath shows that LUN is not accessed by another HBA through another SP. (LUN will trespass). The information is displayed as follows:

Jan 29 16:01:07 linuxtst01 kernel: qla2400 0000 LOOP DOWN detected 08: LOOP DOWN detected (2).

Jan 29 16:01:18 linuxtst01 kernel: qla2x00: FAILOVER device 0 from 5006016039a028a8-> 5006016839a028a8-LUN 00, reason=0x2

Jan 29 16:01:18 linuxtst01 kernel: qla2x00: FROM HBA 0 to HBA 0

Jan 29 16:01:19 linuxtst01 cmafcad [6362]: Host controller 129 status change.Status is now Loop Degraded.

Jan 29 16:01:21 linuxtst01 kernel: qla2x00: FAILOVER device 0 from 5006016839a028a8-> 5006016a39a028a8-LUN 00, reason=0x2

Jan 29 16:01:21 linuxtst01 kernel: qla2x00: FROM HBA 0 to HBA 0

Jan 29 16:01:23 linuxtst01 kernel: qla2400 0000:08:00.0: Scheduling rescan for new luns...

Jan 29 16:01:23 linuxtst01 kernel: qla2400 0000:08:00.1: Scheduling rescan for new luns...

Jan 29 16:01:24 linuxtst01 kernel: qla2x00: FAILOVER device 0 from 5006016a39a028a8-> 5006016939a028a8-LUN 00, reason=0x2

Jan 29 16:01:24 linuxtst01 kernel: qla2x00: FROM HBA 0 to HBA 1

It is obvious that PowerPath did not fail over, but QLogic native failover was activated.

Check the ql2xfailover parameters of / etc/modprobe.conf (RHEL host) or / etc/modprob.conf.local (SuSE host).

Solution:

Change the ql2xfailover parameter value to 0 to prevent native failover. Add options qla2xxx ql2xfailover=0 ConfigRequired=0 to / etc/modprobe.conf, recompile initrd, and restart. After restarting, make sure that "cat / sys/module/qla2xxx/parameters/ql2xfailover" returns 0.

After reading the above, do you know how to parse the host HBA in the Linux/Unix system can not find LUN path display errors and LUN-related errors? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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