AIX > Tips & Techniques > Systems Management

How to Maintain a Virtual I/O Server With FBO

Editor’s Note: This is the second of a two-part series on Virtual I/O Server (VIOS) care and feeding.

Part one discussed how to perform backups of the VIOS and update it. This installment offers a few tips and tricks that can help maintain a VIOS, including how to take advantage of file backed optical (FBO).

Useful Commands and Tips

In production, a best practice is to run dual VIO servers. This allows for maximum redundancy for networking and storage while still having the flexibility to perform upgrades without an outage. Dual VIO servers allow the use of Link Aggregation Control Protocol (LACP) or other aggregation on the shared Ethernet adapter (SEA) without network interface backup (NIB). As long as each VIOS is connected to a separate network switch, full redundancy is provided with SEA failover. And the full bandwidth of the network adapters on the primary VIOS is now available for use.

SEA failover performance can be improved by setting portfast trunk on the switch ports and by activating dead gateway detection with a ping time of two seconds. (To learn more, see the PowerVM User Group session 5 on PowerVM Best Practices.)

SEA failover performance can be improved by setting portfast trunk on the switch ports and by activating dead gateway detection with a ping time of two seconds. (To learn more, see the PowerVM User Group session 5 on PowerVM Best Practices.)

When configuring the fibre channel (FC) adapters, num_cmd_elems and max_xfer_size might have to be tuned for each. For N-Port ID Virtualization (NPIV), the VIOS must be set to at least as high a value as any client LPARs. Keep in mind that the padmin account is able to gain root privileges, so ensure that the password is well protected. With root privileges the user has access to anything root can see. There’s no need to become root to run the topas utility—simply type in topas_nmon –f or topas_nmon -? (the -? provides a list of options).

If asked to gather data for IBM, it will be necessary to set a debug mode to gather the data. The steps involved in capturing debug output from padmin for IBM are described here.

As padmin, it’s possible to get a command history (using the fc -l command) as well as the contents of the global command log (lsgcl) so the actions taken can be reviewed.

$ fc -l
725     lsrep
726     backupios -file /usr/local/backups/b750viobkp
727     exit
728     lsmap -vadapter vhost0
729     fc –l

$ lsgcl | grep "Aug  9 2013"
Aug  9 2013, 08:25:35 root     ioslevel 
Aug  9 2013, 08:59:22 padmin   license  -swma
Aug  9 2013, 09:00:29 padmin   lsmap  -vadapter vhost0
Aug  9 2013, 09:01:29 padmin   lsgcl 

For advice on a VIOS configuration, consider running the VIOS Advisor, which is now part of the latest VIOS but can also be downloaded here.

Finally, there’s an undocumented way to redirect output when running commands on a VIOS as padmin. The trick is to use tee:

lsmap –all –npiv  | tee npivdata.txt


FBO is a great way to provide DVD access to LPARs without having to move the CD around. My VIOS normally boots from internal disk with two disks mirrored to each other in rootvg. I add a third disk and put it into its own volume group (VG), which I use as a repository. Whenever I get DVDs with software, I rip them to an ISO image that is then uploaded to the repository. Additionally, a mksysb image can be loaded and an LPAR can be booted from it.

So using hdisk2 as my third disk I create a VG:

mkvg –y datavg hdisk2
mkrep –sp datavg –size 10G

This can be increased later and creates:

/dev/VMLibrary     10.00      5.85   42%        7     1% /var/vio/VMLibrary

We can now load images into the repository from an ISO we have on NFS:

mkvopt -name rhelboot64  -file /usr/local/nfsmnt/rhel-64bit-basedvd.iso

This takes the ISO and copies it as follows:

$ ls -l /var/vio/VMLibrary
-rw-------    1 root     staff     237981696 Jul 25 13:14 rhelboot64

To list the repository:

$ lsrep
Size(mb) Free(mb) Parent Pool         Parent Size      Parent Free
   10199     5989 datavg                   279552           157696
Name                                                  File Size Optical         Access 
rhelboot64                                                  227 None            rw     

In order to use the repository, the virtual host has to be assigned a virtual SCSI FBO adapter; do so with:

mkvdev -fbo -vadapter vhost0
vtopt0 available

Multiple vtopt devices for a client can be created, if desired:

loadopt -vtd vtopt0 -disk rhelboot64 

This example would mount rhelboot64 as if it were a local CD. To unmount it, use:

unloadopt -vtd vtopt0

Also, rmvopt removes an image; rmrep removes a repository; and lsvopt lists the state of the vtopts:

$ lsvopt
VTD             Media                                                 Size(mb)
vtopt0          No Media                                                   n/a

Consistency and Discipline

Maintaining a VIOS isn’t a difficult job. It just requires some consistency and a disciplined approach. The use of dual VIO servers makes maintenance far simpler because it allows for updating one VIOS at a time without taking an outage. A well-maintained VIOS will make a huge difference to the stability and success of the virtualized environment it supports. These tips should help ensure the VIOS is well maintained.

Jaqui Lynch is an independent consultant, focusing on enterprise architecture, performance and delivery on Power Systems with AIX and Linux.

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