AIX

Is it necessary to put system into single user mode for applying aix 5.3 TL8 on a aix 5.3.5.0 system ?

Is the TL8 installation not totally safe ?

thank you.

If you want to apply a ML/TL properly, you'll have to follow the installation documentation that comes with it. If you want to skip any step or something, I bet your support might ask, if you have followed the steps in that documentation and if you say you didn't, they might pick that up and ask you to do it that way.
For single user mode, I can't say if it is definetly necessary, but I guess they want just to make sure, nothing else connects to the box.
Maybe you can get along with a /etc/nologin but if you want to be totally sure, you do a correct update, follow the docu which comes with every ML/TL.

We don't have TL8 yet live, we have currently max. 5300-07-02-0806 installed. If you don't have a dire need for applying TL8, I would not apply it^^ I think always 1-2 versions behind is ok - no idea how new TL8 is though.

Thanks a lot for your very soon reply !
I am very agree with your advice about staying 1/2 version behind.
I decided to apply TL8 as it was created 6 Month ago, and as AIX 6 is now there.

Concerning TL8 application, the procedure isn't talking about any application stop, nor single user mode. That's why I am asking all of this.

6 months sounds stable. Best follow the manual for it. Pick a box that is only for testing or at least not that important for a test install - have it run for some days and if everything is still ok, apply it to your prod boxes.

by "manual", do you mean "installation tips" like following link ? --->
http://www-933.ibm.com/eserver/suppo...300-08-00-0818

Yep, that looks like it. If there is no extra documentation coming with the CD/DVD or download, then take this.

Applying TL8 to a TL6 machine caused all sorts of problems in my last project. The reason being that the procedure controlling the installation was quite "alpha", so to say. This was in late July/beginning of August. (I remember lots of unfulfilled dependencies and all sorts of nasty effects).

What definitely helped was to upgrade the machine to TL7 and only then upgrade it to TL8. This worked flawlessly.

If memory serves correctly a colleague told me there were no problems when upgrading from a 5.3-0 installation but i could remember wrongly.

Bottom line: TL8 is flagged "handle with extreme care" in my book, maybe they have sorted out the issues with the installation process in the meantime maybe they haven't. I wouldn't bet on IBM having taken care. Create a known-to-be-working backup before starting the upgrade, if you have a mirrored rootvg you might want to do an alternate disk migration.

Don't let petty users press you to hasten the installation process - take your time. If they have a problem with the downtime they should have bought more hardware (to allow takeover) in first place instead of pestering you.

I hope this helps.

bakunin