SUMMARY: SA Wish list for Solaris 8

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Date: Sun, 7 Nov 2004 23:30:55 -0500
To: sunmanagers@sunmanagers.org

I had asked for an SA wish list of console access. for a way to
limit /tmp (real memory) from users taking all
of it and crashing the systems. For an emergency back-door
program to the systems. I got some good replies...
Thanks to everyone who replied.

Chris send the nicest most simple tool (attached below). Use
script as in "script console-file". And then all other users
can view with a tail -f console-file. This is great and
simple. I run it from inside the tool called "screen". Screen
has been around for a long time (virtual terminal that you can
reconnect to later on). I no longer hang my console...
if I time-out my jobs are still running etc. The combination of
screen and script are very good. Also, with
screen I can log-out of my screen session and let someone else
take over at the console while I look at the
tail -f console-file! Perfect!

In terms of hardware solutions... I already have Alpha VCC,
Cisco Terminal Server, and Annex TCs. There were some
good Hardware recommendations made. What I as looking for is
the combo of "script" and "screen" as described
above for SAs to share the hardware Serial Terminal Servers we
are using.

Darren Dunham sent an answer to the question of /tmp and
limiting it. I had seen the man page.. for mounting
manually, I had not seen options that could be put on vfstab or
/etc/system to make it come-up like that after
reboot. Yes, it is based on percentages. I can come up without
swap on critical systems and them added with the
correct mount option to mount_tmpfs (see below).

Thanks to:
Chris <kingsqueak@kingsqueak.org>
Michael DeSimone <michael@desimone.net>
"George Monappallil" <gmonappallil@yak.ca>
Darren Dunham <ddunham@taos.com>
Gregory Shaw <shawga@galadriel.stortek.com>

Chris <kingsqueak@kingsqueak.org>
You asked a few questions in there. (Yes, I did... wish list ...
at least 3 wishes!)

For other users to observe a terminal session, if they are also
able to log in, it's pretty simple though a bit crude. Simply
run a 'script' session and have the other users tail -f the
output file, they will see everything that comes and goes from
your session. It's also handy of course as it tracks a session
for future reference.

For emergency access to a Sun system that is on enterprise Sparc
hardware you should consider a serial terminal. Something like
this product.

http://www.perle.com/products/prod_family/serial_servers/iolan_pl.html

Or even more basic.
http://www.dcbnet.com/datasheet/ss1ds.html

** thanks this was very good. I already have good serial
consoles Alpha VCC, Cisco Terminal Servers and older
legacy Annex Terminal Concentrators. But the script... with
screen works great. Thanks.

Darren Dunham <ddunham@taos.com>
> I am looking for a way to limit the amount of memory that can
be
> taken from /tmp. I want to limit or leave space available on
> /tmp. I would like to l leave 500MB on most servers and 1GB
on
> the big clusters. Can it be done with either
> tmpfs:tmpfs_maxkmem or tmpfs:tmpfs_minfree and how? What
would
> the kernel settings be on /etc/systems? Please make sure that
> you done it if you make a suggestion I would like something
> from someone who has implemented it!

Sorry, the system can use all swap until tmpfs filesystems have
no more
free space. You can use a UFS filesystem to guarantee space
remains.

> Reason: Users and sometimes fill /tmp and caused the system
to
> hang. If you are lucky you get there through the console and
> remove the offending files. If not you might not have enough
> resources to get in. On big clusters it can panic the nodes
> when RPC goes south. Ill like to limit or reserve space away
> from /tmp.

Oh, that's the other direction. You don't want to limit what
can be
taken from /tmp, you want to limit what /tmp takes from memory.

That's easy. Read 'man mount_tmpfs' and look at the size=
parameter.
Unfortunately, that's a fixed limit. It's not based on the
amount of
memory remaining. So if your limit is 2G and you've only got 1G
free,
it won't help you.

** As always thanks for the reply. I was not able to get it to
come-up after reboot with any options in restricted mode after
reboot. I can mount it with a reserve from the command line.
Myabe I am missing options on vfstab... I'll put a case with SUN
to see if they have anything.

Michael DeSimone <michael@desimone.net>
For the console if you have the budget, I would recommend this
http://www.thinklogical.com/products/scs_480.html
uses ssh can have as many people view as you want and keeps a
256k
buffer of the console - which is quite bit. So if the system
goes down
and nobody is logged on when you hop on the console you can see
what the
last messages were before death. Very reasonably priced, I love
mine and
just ordered another one.

** Thanks

"George Monappallil" <gmonappallil@yak.ca>

I am looking for such a tool currently, so it would be really
helpful if
you summarize at the end.
Thanks in advance.

-George

Gregory Shaw <shawga@galadriel.stortek.com>
It's not a software program, but cyclades console servers allow
this behavior.

Carlos

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