More about LV's 1

[solid7]

Most of you know by now that I'm a newbie, and that I ask a lot of dumb question about LVM, and the AIX filesystem.

So, please give me some space to ask just one more silly question - Perhaps I have not covered it yet in the Redbooks, but when is it appropriate to use new logical volumes in a single workstation? (one physical volume, no other connected machines, etc.)

Should I be making logical volumes for each application? For each user? Something else?

Additionally, what is the intended use for the system defined folders, like /usr, /tmp, etc...

Most of my applications intall, by default, into the /usr directory. However, I'm not sure that I want (or don't want) that. I do know that I'm running multiple versions of the same application, and I'd like to be able to run them simultaneously, so I don't want to overwrite, or do runtime installations.

Thanks again for all of your help!


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[ggauthier]

On larger systems, I will usually* create one LV per app. This segregates the applications from each other and the operating system. Thus, if one goes wild and fills up their filesystem, the other applications are protected.

On a single workstation, I would probably not use too many LVs. This is because you have more limitations on disk space, and each filesystem will have a buffer (a percentage free). That buffer space can add up quickly.

*This truly depends on the specific app and the nature of the app.

gg

 

[solid7]

So would you recommend that I NOT use ANY logical volumes?

Second, let's say that I want to migrate my data later to a more powerful machine - I currently use an RS6000, and will eventually buy a POWER series - is it smart to create user data on a unique logical volume, rather than a subfolder of the root directory?

I'm sorry if this seems basic - I just haven't quite figured out what the intended purpose of logical volumes is, and perhaps that's because I don't use them in context. (and maybe never will)

Additionally, I'm wondering if you can help me (better) understand how I should be making use of the system defined folders, and when/how to install software to other folders.

Thank you.


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[ggauthier]

I suggest that you do use LVs and JFSs. But application installations are not black-and-white. Some apps will very likely be installed directly in /usr, while others will be installed in their own LV and possibly their own volume group.

But, you may want to create a /usr/local filesystem to cover /usr/local/bin, /usr/local/man, etc.

This is very dependent upon your needs.

For home directories, though, it is black-and-white for me ... user home directories never belong with the OS or other application installations. Always create a filesystem for the users. A user should never be able to bring the OS or application filesystems to 100% utilized.

That's the beauty of LVs ... you can segregate your data and users and apps to whatever level you need.

For example, if you have Oracle installed, you can create multiple databases on multiple LVs such that they never share disk space. This can help (or hurt) performance, but it ensures that each database gets the disk space that they need and cannot "steal" space from another database.

As for standard directories and their uses, check out Chapter 5, "Filesystems"

http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixuser/usrosdev/usrosdevtfrm.htm

gg

 

[costiles]

The main reasons that I create additional logical volumes are: 1) To segregate problem applications - problem meaning I do not know how big the files will be and I don't want to overwhelm an existing application 2) To position an application for max speed - ie - outer edge of disk 3)To allow mounting or dismounting for backup purposes, etc. If I do not want to backup a particular app- I can umount it. This is useful when you want to move a base application without all the data files. The base application would be on one logical volume and the data in another. They could be like: /usr/appbase and the other might be /usr/appbase/DATA. So to keep from copying/backing up the data I would umount it.

 

[solid7]

It's been awhile, and I've learned alot. I can now say that I understand more, and I totally agree with what you've posted.

I'm not a network adimin, but the logical volumes have proved worth their weight in gold for "problem apps." No doubt about it.

Thanks for the reply.


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