I remember reading this interesting document about some challenges renaming AIX devices.
http://gibsonnet.net/aix/ibm/The_Fun_of_Oracle_RAC_ASM_and_Device_Names.doc
This poor guy had to jump through some hoops to rename some disk and network devices in a clustered AIX (Oracle RAC) environment.
This comment stayed with me:
The easy way to get network adapters and disk names to match between systems would be to run something like
# chdev l old_name n new_name
Except, this command option does NOT exist.
Since then Ive always been on the look out for an easy way to rename devices in AIX.
In particular in large clustered environments where it is sometimes very important to have the same disk and network device names in sync across all nodes in a cluster. And besides, its a lot easier to verify a cluster configuration if the hdisk names are all the same. Matching PVIDs works but it requires a lot more effort! For example, knowing that hdisk123 is the same device on all nodes makes life easier than scanning lspv output for a PVID like 00f6048868b4gead. Of course you can script things to make this easier but it would be great if you didnt need to do this and that there was a way to rename devices as needed, without resorting to unsupported methods.
Well, this is no longer an issue for AIX.
Starting with AIX 7.1, you can now easily rename devices. A new command called rendev was introduced to allow AIX administrators to rename devices as required.
From the man page:
The rendev command enables devices to be renamed. The device to be renamed, is specified with the -l flag, and the new desired name is specified with the -n flag.
The new desired name must not exceed 15 characters in length. If the name has already been used or is present in the /dev directory, the operation fails. If the name formed by appending the new name after the character r is already used as a device name, or appears in the /dev directory, the operation fails.
If the device is in the Available state, the rendev command must unconfigure the device before renaming it. This is similar to the operation performed by the rmdev -l Name command. If the unconfigure operation fails, the renaming will also fail. If the unconfigure succeeds, the rendev command will configure the device, after renaming it, to restore it to the Available state. The -u flag may be used to prevent the device from being configured again after it is renamed.
Some devices may have special requirements on their names in order for other devices or applications to use them. Using the rendev command to rename such a device may result in the device being unusable. Note: To protect the configuration database, the rendev command cannot be interrupted once it has started. Trying to stop this command before completion, could result in a corrupted database.
This functionality was required to help simplify cluster device configuration with the new Cluster Aware AIX (CAA) feature in AIX 7.1.
Ill be blogging about CAA in a future post.
Here are some examples of using the rendev command on AIX 7.1 (GA) system. In the first example I will rename hdisk3 to hdisk300. Note: hdisk3 is not in use (busy).
If the disk had been allocated to a volume group, I would have needed to varyoff the volume group first.
# lspv
hdisk0 00f61ab2f73e46e2 rootvg active
hdisk1 00f61ab20bf28ac6 None
hdisk2 00f61ab2202f7c0b None
hdisk4 00f61ab20b97190d None
hdisk3 00f61ab2202f93ab None
# rendev -l hdisk3 -n hdisk300
# lspv
hdisk0 00f61ab2f73e46e2 rootvg active
hdisk1 00f61ab20bf28ac6 None
hdisk2 00f61ab2202f7c0b None
hdisk4 00f61ab20b97190d None
hdisk300 00f61ab2202f93ab None
Easy!
Next, Ill rename a virtual SCSI adapter. I renamed vscsi0 to vscsi2. Note: I placed the adapter, vscsi0, in a Defined state before renaming the device.
# rmdev -Rl vscsi0
# lsdev -Cc adapter
ent0 Available Virtual I/O Ethernet Adapter (l-lan)
ent1 Available Virtual I/O Ethernet Adapter (l-lan)
vsa0 Available LPAR Virtual Serial Adapter
vscsi0 Defined Virtual SCSI Client Adapter
vscsi1 Available Virtual SCSI Client Adapter
# rendev -l vscsi0 -n vscsi2
# lsdev -Cc adapter
ent0 Available Virtual I/O Ethernet Adapter (l-lan)
ent1 Available Virtual I/O Ethernet Adapter (l-lan)
vsa0 Available LPAR Virtual Serial Adapter
vscsi1 Available Virtual SCSI Client Adapter
vscsi2 Defined Virtual SCSI Client Adapter
Now Ill rename a network adapter from ent0 to ent10. I bring down the interface before changing the device name
# lsdev -Cc adapter
ent0 Available Virtual I/O Ethernet Adapter (l-lan)
ent1 Available Virtual I/O Ethernet Adapter (l-lan)
vsa0 Available LPAR Virtual Serial Adapter
vscsi1 Available Virtual SCSI Client Adapter
vscsi2 Defined Virtual SCSI Client Adapter
# ifconfig en0
en0: flags=1e080863,480<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST,GROUPRT,64BIT,CHECKSUM_OFFLOAD(ACTIVE),CHAIN>
inet 10.1.20.19 netmask 0xffff0000 broadcast 10.153.255.255
tcp_sendspace 262144 tcp_recvspace 262144 rfc1323 1
# ifconfig en0 down detach
# rendev -l ent0 -n ent10
# lsdev -Cc adapter
ent1 Available Virtual I/O Ethernet Adapter (l-lan)
ent10 Available Virtual I/O Ethernet Adapter (l-lan)
vsa0 Available LPAR Virtual Serial Adapter
vscsi1 Available Virtual SCSI Client Adapter
vscsi2 Defined Virtual SCSI Client Adapter
# rendev -l en0 -n en10
# chdev -l en10 -a state=up
en10 changed
# mkdev -l inet0
inet0 Available
# ifconfig en10
en10: flags=1e080863,480<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST,GROUPRT,64BIT,CHECKSUM_OFFLOAD(ACTIVE),CHAIN>
inet 10.1.20.19 netmask 0xffff0000 broadcast 10.153.255.255
tcp_sendspace 262144 tcp_recvspace 262144 rfc1323 1
If you want to be creative you can rename devices to anything you like (as long as its not more than 15 characters). For example Ill rename vscsi2 to myvscsiadapter.
# rendev -l vscsi2 -n myvscsiadapter
# lsdev -Cc adapter
ent1 Available Virtual I/O Ethernet Adapter (l-lan)
myadapter Available Virtual I/O Ethernet Adapter (l-lan)
myvscsiadapter Defined Virtual SCSI Client Adapter
vsa0 Available LPAR Virtual Serial Adapter
vscsi1 Available Virtual SCSI Client Adapter
And in the last example Ill demonstrate changing virtual SCSI adapter device names on a live system.
This is single disk system (hdisk0), with two vscsi adapters.
# lspv
hdisk0 00f6048868b4deee rootvg active
# lspath
Enabled hdisk0 vscsi0
Enabled hdisk0 vscsi1
# lsdev -Cc adapter
ent0 Available Virtual I/O Ethernet Adapter (l-lan)
ent1 Available Virtual I/O Ethernet Adapter (l-lan)
vsa0 Available LPAR Virtual Serial Adapter
vscsi0 Available Virtual SCSI Client Adapter
vscsi1 Available Virtual SCSI Client Adapter
We ensure the adapter is in a Defined state before renaming it. This will fail otherwise.
# rmdev -Rl vscsi1
vscsi1 Defined
# lsdev -Cc adapter | grep vscsi
vscsi0 Available Virtual SCSI Client Adapter
vscsi1 Defined Virtual SCSI Client Adapter
Now we rename the adapter vscsi1 to vscsi3.
# rendev -l vscsi1 -n vscsi3
# lsdev -Cc adapter | grep vscsi
vscsi0 Available Virtual SCSI Client Adapter
vscsi3 Defined Virtual SCSI Client Adapter
That was easy enough. Now I need to bring the adapter and path online with cfgmgr. The lspath output displays an additional path to vscsi3.
# lspath
Enabled hdisk0 vscsi0
Defined hdisk0 vscsi1
# cfgmgr
Method error (/etc/methods/cfgscsidisk -l hdisk0 ):
0514-082 The requested function could only be performed for some
of the specified paths.
# lspath
Enabled hdisk0 vscsi0
Defined hdisk0 vscsi1
Enabled hdisk0 vscsi3
Now I need to remove the old path to vscsi1. The path to vscsi3 is now Enabled. The adapter, vscsi3, is in an Available state. All is good.
# rmpath -l hdisk0 -p vscsi1 -d
path Deleted
# lspath
Enabled hdisk0 vscsi0
Enabled hdisk0 vscsi3
# lsdev -Cc adapter | grep vscsi
vscsi0 Available Virtual SCSI Client Adapter
vscsi3 Available Virtual SCSI Client Adapter
The same steps need to be repeated for the vscsi0 adapter. This is renamed to vscsi2.
# rmdev -Rl vscsi0
vscsi0 Defined
# lsdev -Cc adapter | grep vscsi
vscsi0 Defined Virtual SCSI Client Adapter
vscsi3 Available Virtual SCSI Client Adapter
# rendev -l vscsi0 -n vscsi2
# lsdev -Cc adapter | grep vscsi
vscsi2 Defined Virtual SCSI Client Adapter
vscsi3 Available Virtual SCSI Client Adapter
# lspath
Defined hdisk0 vscsi0
Enabled hdisk0 vscsi3
# cfgmgr
Method error (/etc/methods/cfgscsidisk -l hdisk0 ):
0514-082 The requested function could only be performed for some
of the specified paths.
# lspath
Defined hdisk0 vscsi0
Enabled hdisk0 vscsi2
Enabled hdisk0 vscsi3
# rmpath -l hdisk0 -p vscsi0 -d
path Deleted
# cfgmgr
# lspath
Enabled hdisk0 vscsi2
Enabled hdisk0 vscsi3
Thats it. Both adapters have been renamed while the system was in use. No downtime required.
# lsdev -Cc adapter | grep vscsi
vscsi2 Available Virtual SCSI Client Adapter
vscsi3 Available Virtual SCSI Client Adapter
# lspath
Enabled hdisk0 vscsi2
Enabled hdisk0 vscsi3
Please refer to the AIX 7.1 command reference for more information on this new command:
http://publib.boulder.ibm.com/infocenter/aix/v7r1/topic/com.ibm.aix.cmds/doc/aixcmds4/rendev.htm
And by the way, heres a draft of what Ive been working on for the last 5 weeks:
IBM AIX Version 7.1 Differences Guide:
http://www.redbooks.ibm.com/Redbooks.nsf/RedpieceAbstracts/sg247910.html?Open
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