At the IBM Power Systems Technical University in October, there was a fascinating session on Disk IO Tuning in AIX 6.1.  I didn't get to see the session, but the presentation slides are well worth reading. Even if you're not running 6.1, the principles and examples will be relevant. The session had Dan Braden as its author and was presented by Steve Nasypany, and it covered topics such as: The importance of I/O tuning Disk basics and performance overview How to improve disk performance Performance monitoring tools Tuning, including queue depth... [More]

Tags:  mount aix chlv chfs log=null ram_disk nmon tuning io no_logging disk topas performance iostat iowait rmfs power_systems queue_depth

If you're unfortunate enough to lose the root password on an AIX host, there is a way of recovering it . You can also recover the padmin password in VIOS if you've lost it. Basically, it's a matter of booting from AIX or VIOS installation media and stepping through the System Maintenance menus. When you do that, the boot file systems come from the installation media, and then you import the rootvg volume group which is on the original disks (the one with the unknown password). At that point you can run the passwd command or edit /etc/passwd.  ... [More]

Tags:  aix padmin password root

<!-- @page { margin: 2cm } P { margin-bottom: 0.21cm } A:link { so-language: zxx } --> Install X-Windows without the pane However hardline you are about the command line, there may just be a time when you need to use X-Windows. Alright, you might not actually need to, but it might just be good to know how to set it up anyway. The Windows menu utility WebSM comes in handy sometimes. I used it recently for the aixpert tool . It allowed me to have a... [More]

Tags:  aix x-windows websm x11_forwarding putty x11 wsm cde common_desktop_environmen... x-server

Not a spitting image If you want to create a DVD image on AIX, you can do it right from the command line, without even touching physical media, using the mkdvd command. It was a wonder back in ... well, a long time ago ... when these new-fangled CDs came out and you could play music and use them as coffee cup holders (not at the same time). But the novelty of having a button on your computer that spits out a CD or DVD at you has somewhat faded. We want an image, but not a spitting image. On AIX you can create an ISO format image of a directory... [More]

Tags:  image dvd mkdvd iso chvopy vio virtual_media loadopt aix vmlibrary vios mkcd mksysb read_only

While you're in the middle of testing a new script, you may be tempted to add it to the cron to see how it goes. That involves: checking the system time using the date command translating that into the format explained by the man page for crontab : minute hour day_of_month month weekday command and setting the command just in time to start before the next minute ticks over. After reworking the script a few times, looking up the crontab command which tells you that the week starts with 0 for Sunday, and minutes come before hours, and not... [More]

Tags:  command regular crontab one-off at schedule script jobs cron aix

"Nothing has changed, but suddenly a service has stopped working." My colleague assured me that no changes had been made on AIX. I had good reason to believe him, as he was a cautious, experienced sys admin, and was in the middle of a change freeze anyway in the leadup to Christmas. In Australia, it is common for companies to have skeleton staff and many people taking their summer holidays, so many companies keep any configuration changes to a minimum. For retail businesses which may have increased sales around the end of December,... [More]

See update at end of post.  From the HMC, you can open a terminal session to the console of an LPAR. I reminisced about green screens and different console connections available to AIX in this post . But I didn't take account of one of them: you can create a virtual terminal session from the VIO Server to an LPAR. When you're logged in as padmin on the VIO Server you can create a terminal session using the mkvt command . mkvt command Purpose Create a virtual terminal connection to a partition. Syntax mkvt   {   -id   lparID } To terminate... [More]

Tags:  lpar padmin terminal_session aix hmc mkvt console vio modem

An IBM Oracle Technical Brief came out in May entitled Oracle Architecture and Tuning on AIX . There's a lot in it, but the good news is that if you're working on an AIX system that was a fresh install of AIX 6.1 or 7.1, then on the whole the default tuning parameters are what you need. If you're still on AIX 5.3, or if your system was migrated from AIX 5.3 to 6.1 to 7.1, you may need to revisit the tuning parameters. Do it anyway, if you can. There are two items which caught my eye especially from this Oracle Technical Brief: Logical Volume... [More]

Tags:  lv pp reorgvg agblksize lvm disk_layout tuning redo_logs performance striping oracle

 When you run some AIX Logical Volume Manager (LVM) commands, the volume group you're working on gets locked. Don't worry. The data is still accessible and users can work away merrily (or grumpily). The lock is put in place to stop other LVM commands which might try to update the same LVM metadata. For example, if you run migratepv to move your data to a new, fast-performing LUN (you hope), you might like to check the state of the volume group (VG). If you try to view the VG while it is locked, you'll get a message such as this: ... [More]

Tags:  volume_group_lock lslv 0516-1201 -l chvg lsvg locked error lspv aix lvm