UNIX for Advanced & Expert Users

I have started a new job which requires AIX admin skills, which I have, and RHEL skills. Does anyone have a cheat sheet that if I know how to solve the problem in AIX how would I do that in RHEL? I was an IBM pre-sales technical trying to keep sales guys honest - not possible. Any other links to training would be good motor. Keep in mind I'm not going to pay $2300 for real RHEL training. Thanks to all that help - I need it

I have found this by typing "mksysb ignite linux pvcreate" into a search engine:-

UNIXguide.net ( AIX, FreeBSD, HP-UX, LINUX, SOLARIS & Tru64)

It's not bad, but a bit out of date now. It gives a you starter I suppose.

Probably the most important thing to understand is that there is another layer to disk management. In a proper OS such as AIX, you would see the disk after cfgmgr and make/extend your volume groups with mkvg or extendvg respectively. For Linux though, you step back to a DOS world initially.

There is the lovely fdisk to slice you disks. You are probably best defiining them as a single whole-disk slice of type 8e which denotes Linux LVM. Then run a pvcreate after which you can vgcreate or vgextend and finally use LV commands to build filesystems.


I hope that this gets you started. I'm on the same insane path myself.

So far, there is no mksysb equivalent.




Robin
Liverpool/Blackburn
UK

Search for rosetta stone unix in google, that may be helpful (I tried to post the URL, but it said I wasn't allowed until I have 5 post).

I went from a RHEL environment to a pure AIX environment, I had no idea I was in for such a shock.

Shock!

I suppose I would be in SHOCK too if I went to pure Linux anything after over 30 years of UNIX.

For years there has been talk of "generic" *NIX - and for many commands, generic works. However, "distributions" of *NIX, including Linux (which is usually lowercase, not upper case) all have there differences.

The little I know of Linux makes me doubt that Linux volume management has not gotten farther than the "divvy/fdisk" like ways that were common +- 12 years ago.

But they are different from using smit (as admin interface) or the *vg, *lv, *fs commands to make, change, remove volume groups, logical partitions, and file systems on AIX. Basically, every *NIX has there own way of doing the administration - and the "rosetta stone" approach is probably an excellent start for you own cheat-sheet.
Rosetta Stone for UNIX

We use HP-UX and RHEL here. Yes, they're different enough from one another that there is a learning curve. AIX isn't so different from HP-UX, but RHEL is a different animal altogether.

The O'Reilly animal books are a good way to learn.

A few quick RHEL transition notes:
- While the LVM is an integral part of any HP-UX or AIX system, it is optional on RHEL. We're not using LVM on any of our RHEL servers.
- /etc/sysconfig/ is where a lot of OS config files can be found
- Google "selinux" it's a security layer that will cause you some frustration if you aren't aware that it's running and what it does.
- system-config-firewall-tui will let you open services for the software firewall.
- yum is the command to install and remove software. yum check-update to check for new updates, and yum update to install them. Software installation and updates occurs through "repos", the config files of which are found in /etc/yum.repos.d/
- mdadm controls the software RAID functionality, RAID-1 mirroring for your OS, for example. This is a different layer entirely from LVM. If you have a commodity server with a hardware RAID controller, you can ignore mdadm.
- If you opted to install the GUI, you can do user management, some system config, and other things via gui apps.

---------- Post updated at 01:23 PM ---------- Previous update was at 01:15 PM ----------

Yes you can fdisk and manually create partitions and filesystems (just like Microsoft Windows does). But nowadays, Linux has a robust and full featured LVM, just like HP-UX and AIX. It also has a high performance software RAID layer, if you're running on a machine without a hardware RAID controller. It also has strong AES256 volume encryption.

Any of these features can operate on a filesystem, a partition, or a full disk, and you can layer these features however you see fit, and it's all matured to enterprise level reliability.

Its come a long ways since 12 years ago.

---------- Post updated at 01:29 PM ---------- Previous update was at 01:23 PM ----------

Not necessarily. Linux LVM, mdadm software RAID, and cryptsetup disk encryption can all operate on whole disks. No partitioning required. And the kernel as well as the grub boot loader have the smarts to boot from them.

Of course you can still do manual fdisk partitioning, as with dos/windows days, and some folks (including myself) still do this out of habit and comfort zone, but it is no longer required.

Linux is certainly capable of using more advanced schemes, but most Linux distributions face pressure to remain compatible with Windows partitioning schemes, since it's often installed alongside Windows... And Windows' methods have barely changed since the 80's, except for the recent GPT upgrade which just extends for larger disks again. Installing on single-disk consumer computers also means there's less need to consider anything else.

I admit I've been a bit resistant to LVM and the like myself. Needing a daemon to deal with your partitions just seems like begging for trouble.