[gregscott]

I have a mystery to solve. I am setting up some AIX servers with some very specific requirements.

The server has one volume group named rootvg. Inside rootvg, there is one hardware RAID 5 set - so just one "disk". And inside this "disk", I need several partitions - /, /home, /var, etc. These need to be real partitions or file systems.

All this works and with some help I was able to navigate "smitty fs" and set them up with the sizes I need.

A couple of the partitions are very deep and don't mount at boot time.

/opt - works just fine.
/opt/aaa - also mounts just fine
/opt/aaa/bbb/ccc - does not mount.

There is no specific directory /opt/aaa/bbb.

I have a hunch my problem is because either (1) - I never specifically setup /opt/aaa/bbb, or (2), /opt/aaa/bbb/ccc is too deep. In the Microsoft world, you can't have partitions inside partitions inside partitions. I'm not sure if the AIX world likes this or not.

I tried this:

cd /opt/aaa
mkdir bbb

and then rebooted but my deep partitions still don't mount at boot time. I tinkered with trying to mount them by hand but I'm not sure how to do this yet.

I'm at the limit of what I've learned so far about AIX LVM. Any advice or pointers to docmentation would be greatly appreciated.

thanks

- Greg Scott

[ross.mather]

The usual cause of the problem will be related to the order that filesystems are mounted in.

I would strongly recommend changing this structure as it is very error-prone.

In theory is should work, what sort of error message are you getting?

[gregscott]

Not really getting any error messages at boot time. But this is a little frustrating because all I see on the VGA console is the login window after it's all booted. There must be a boot log someplace but I don't know where to find it yet.

The other day I found a smitty choice that let me try to mount it. As I recall, it said something about not finding the location or something like that. That was after I created that /opt/aaa/bbb directory. Sorry to be vague - this was a few days ago and the system is 31 miles away right now and not connected to any network.

- Greg

[gregscott]

After scouring through various websites and wikis and any info I can find, it looks like I should have titled this thread differently. From the reading I've done, it seems AIX doesn't really have partitions in the same way as other Unix or Linux implementations.

In AIX, there are volume groups, logical volumes, and then filesystems. A volume group may contain many logical volumes and a logical volume may contain many filesystems. An AIX filesystem is roughly the equivalent of a Unix partition in other implementations.

Just to keep me on my toes, AIX has phycical partitions (PPs). But PPs in AIX are roughly the equivalent of blocks or sectors in other OS's.

So I should have titled this thread "Nested filesystems" instead of "Nested disk partitions".

OK, so understanding all that, I still need to nest those filesystems. Error prone or not, that's the way they need to be for this specific application.

How do I know what order they're mounted? It looks like there's a file named /etc/filesystems that specifies what gets mounted. I'm guessing this is kind of the equivalent of /etc/fstab in other Unix's. Does /etc/filesystems specifiy the order in which filesystems are mounted? Can I edit this file or is this a no-no?

For troubleshooting, right now, all I know how to do is make a change, reboot the system, and then check with the mount command to see what's mounted. This takes forever. There's gotta be a better way. How do I mount a nested filesystem by hand to see what happens? It looks like smitty has some tools that might help - maybe there are some mount command switches that could be useful?

There must be some sort of boot log that shows an audit of what happened at boot time. This would help me chase down what's going on. How do I look at this?

One more question - I just ordered "AIX 5L Administration" from Amazon.com. Did I order a usable book? It's publication date is 2002 so it seems a little dated - but it has a writeup on LVS.

I don't like stumbling around in the dark here and it looks like I will be doing more AIX admin work soon. What additional books should I grab to get up to speed?

thanks

- Greg Scott

[astralvoid]

The problem you are having is that AIX will allow you to set up multiple mount points within any file system, but remember that once you mount /filesystem, it overlays any "deeper" directory structure or files that was already in place.

The previous file is still there, but you wont have access to it until you unmount the most recently mounted filesystem.

Like the previous person mentioned, during auto bootup, filesystems are generally mounted in the order they are listed in the /etc/filesystems file. Have you verified the order they are listed there?

Hope this helps.

[duke900ssd]

Before you spend any more on old books, try a google for:
site:redbooks.ibm.com aix lvm
or just go to:
IBM Redbooks
and search from there.

Most of what you could possibly want to know is available for free download in PDF format.

A google for:
site:ibm.com aix administration
should also give you a lot of usefull stuff to get you going, like the Administration Guide, or even the Certification Study Guide.

IBM documentation is usually very good, the only common problem is finding it! Hence the use of google to search their site.

[astralvoid]

I purchased "AIX 5L Administration" several years ago and actually find it to be very relavent now even though it is several years old.

[gregscott]

Thanks for all the advice. Here is how it turned out. It seems so simple now . . .

When I used smitty to create /opt/aaa/bbb/ccc, it really created a logical volume named /dev/lv0 and told me its mount point was /opt/aaa/bbb/ccc. Except it didn't tell me this in language I understood at the time. And it didn't create the directories, so the mount points didn't exist. That was the whole problem.

The question was asked earlier about what error message I saw when trying to mount this. And now I know how to find the answer. At boot time, the VGA console has a little window in the upper right corner with a log of everything going on at boot time. The monitor was a little bit far away and I literally couldn't see the text fly by earlier - but looking more closely the other day I saw what was going on. It complained about not finding the directory.

I also learned how to mount this by hand - pretty simple - mount /dev/lv0 {mount-point}.

Well, that was the key. That, and what I incorrectly thought were traditional Unix partitions that really were AIX logical volumes.

The whole thing came down to this -

cd /opt/aaa
mkdir bbb
cd bbb
mkdir ccc
mount /dev/lv0 /opt/aaa/bbb/ccc

It all works now.

That dated AIX book has a helpful writeup on all this starting on page 191. I also found some stuff in several IBM publications. It just took a while for it to sink in.

- Greg

[alasdairb]

The couple of other things you were looking for, that AIX console log
alog -t console -o
if you want to make a directory structure in one command, (within an already mounted filesystem)
mkdir -p /aaa/bbb/ccc/ddd/eee/fff
to set ownership
chown -R name.group file will sort the permissions.