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AIX IP Aliases

May 10, 2012 - 00:00 — chris

With AIX you normally want to administer IP aliases with smit or HACMP (PowerHA). However there are times when you dont want them coming back after a reboot. To accomplish this you want to use the UNIX general ifconfig command.

To add an IP alias follow this methodology:

# ifconfig $INTERFACE alias $ALIAS netmask $NETMASK


Example:

# ifconfig en6 alias foo.example.com netmask 255.255.255.128

To remove an IP alias follow this methodology:

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GPFS filesystem out of inodes

April 3, 2012 - 12:35 — chris

I have a customer that wants to have some system WPARs hosted on GPFS, and in turn managed by HACMP. Most of this is simple enough in its components but can get complex in its integration.

One interesting issue I encountered with this configuration is that the default number of inodes that are configured in GPFS are not enough to host multiple LPARS.

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AIX PowerVM/VIO convert fom LV vscsi disk to SAN disk

February 24, 2012 - 22:18 — chris

I was working on a customer system performing some PowerVM (VIO) updates when I noticed that one of the client machines was configured to use vscsi Logical Volume (LV) instead of SAN disks (LUNs). Whats worse is that one of the underlying VIO disks providing the LV was failing. We had raid 5 SAN LUNs available that were mapped though redundant VIO servers, I decided to fix the issue. Of course it couldn't be easy and so I'm sharing.

On the VIO client named server1, rootvg was originally configured to be mirrored between the dual VIO servers named vio1 and vio2.

LINUX private cloud SAN considerations.

February 21, 2012 - 21:58 — chris

I've been considering building out an open source private cloud utilizing mostly used equipment. One of the few pieces of equipment that I'm considering to purchase new is the disk subsystem. Here I'm going to go into that consideration, no technical details only high level technical considerations (sorry).

My requirements are simple. Large cheap disks, seamless automatic disk failure recovery, full redundancy, accessible by older commodity hardware, and since rack space is a ongoing cost, I'd like the overall footprint to be small.

AIX what Process ID has a TCP or UDP port open?

February 5, 2012 - 20:07 — chris

On stock (unmodified) AIX it isn't as easy to trace what TCP/UDP port is being help open to the controlling process. If you are running on Linux or have the open source tool lsof installed its quite simple.

Say for instance I want to see what process is binding to an arbitrary port. In this example I'll use ssh. First I'll provide and example the native AIX way, and then I will provide an example with lsof.

Remember well know ports are often registered in the /etc/services file.

AIX VIO 802.1q Virtual ethernet unavailable

February 4, 2012 - 23:32 — chris

The other day I came across an interesting problem. A virtual adapter on a VIO server that had second trunk priority did not come up when the profile was reactivated, although networking was still active. This seemed contrary to conventional wisdom, so I happily rolled up my sleeves and waded in to find out why.

AIX split tgz files

February 1, 2012 - 23:25 — chris

AIX is a great operating system but it lacks some of the accoutrements of LINUX. For instance the native tar command doesn't support compressing files with command line options like tar -czf file.tgz. To accomplish this you need to pipe commands together.

To create a tgz file:

tar -cvf - ./lppaix61_tl05_sp06-installable/ | gzip -c > file.tgz

To extract a tgz file:

gzip -dc file.tgz | tar -xvf -

AIX VIO vscsi disks VTD path health

January 31, 2012 - 23:23 — chris

When you have a AIX LPAR that uses VIO presented vscsi disks from dual VIO servers, you often have to check the health of these disks. Think rebooting a VIO server.

I often use a command something along the lines of this. to check on all my affected VIO client LPARS.

dsh -N HOST_LIST "lspath |grep -v Enabled"

Once we know the state of the paths (from above) we can make sure that each disk has two paths, consider this for your local system:

AIX dsh parallel ssh execution

January 30, 2012 - 23:02 — chris

One of the commands I truly love is dsh. It allows parallel ssh execution across multiple servers. This is exceptionally useful when executing long running jobs on multiple servers. dsh is distributed with AIX as part of the csm.dsh fileset on aix 6.1 and was moved to dsm.dsh on AIX 7.1.

Many admins will write a command line tool or script that does this in serial. Consider this, a serial execution of a one minute job across 100 servers will take over an hour and a half, with dsh the same job can be done in minutes, depending on your dsh fan-out settings.

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