[Techtalk] unix to linux migration- why?

[R. Daneel Olivaw]

Hi there,

Le Fri, 14 Jul 2006 12:22:25 -0700
Carla Schroder <carla at bratgrrl.com> a écrit:

> My little geekpersons, I am researching why anyone would want to
> ditch their nice muscular Unix server- AIX, Solaris, HP-UX,
> whatever-the-hey- for some ratty lil hippie OS like Linux or one of
> the BSDs. I will stipulate that Linux/BSD are proven as good enough
> for just about anything; so what other reasons would compel such a
> move?

First of all, be known that I know AIX abit, use hp-ux production
servers and have switched from SCO UnixCrap to Linux completely.

1/ SCO vs Linux
SCO was (those who tell you it still 'is', are suffering time/space
distortion and should urgently go to sickbay) the only really available
unix on i386 platforms. It had some very nasty bugs (lpd administration
was a hell) flaky licencing schemes (as soon as you added a
multiprocessor licence, you couldn't install more software) and an old
fashioned monolythic kernel approach (needed to compile the kernel if
you wanted to change your IP address). Therefore, as soon as Linux
kernels came in exploitable distributions, we progressively switched to
it and till then (6 ? 8? years now) we had not a single problem with it
that couldn't be easily resolved by an average skilled unix admin (me).
It now runs flawlessly our centralized Cobol (oh yes, I was talking
about time warp, well, ...) application, in addition to the usual
services it provides "out of the box" (printing, networking,
firewalling, windows filesharing, ...)

2/ hp-ux vs Linux
HP-UX runs on specific platforms (PA-Risc and itanium) and provides
hardware scalability and modularity unknown to the common i386
platforms. Experience proves that even under VERY high pressure, hp-ux
tends to smoothly manage the load, unlike one of my bad Linux
experiences. Now, pricing is a key point. An average HP PA Risc server
outranges the prices of an i386 architecture. Therefore, if ABSOLUTE
stability is needed, you'd switch to hp-ux. Don't get me wrong : Linux
IS stable, most of our customers rely on it everyday. However,
depending on kind of service you provide, redundancy you are able to
manage yourself and money you can spend, you may not yet choose an i386.
New bias : platform makers (including HP) produce better machines now,
and maybe the gap is narrowing ... 

3/ aix vs Linux
hey, I had an AIX once, and the administration tools (text based :
smit & al) are crap. It ran smoothly, but it didn't suit me. All common
unix tasks became complex at once : list active printers, add an
account, setup networking, ... they had a tool for everything, but none
that would exist elsewhere. Error diagnosis was impossible without a
special training from IBM ... in fact, AIX was not a competitor to
Linux, but to hp-ux, and in that struggle, aix lost. We needed X25
support, hp-ux had an excellent one (x25 on aix is a pain in the ...).

Now, I have no experience on Solaris or other unices. Nor would I argue
for BSD, as I have no production server running it (Cobol runtime
support, is a deadly point for our programs).

Maybe some of these points have changed, but here are the main
advantages/drawbacks :

Linux advantages:
- cheaper hardware (multiprocessing, hardware RAID, and so on)
- good support (something you will pay, but it's the same as for others)
- multi-purpose (everything you dream of is shipped)
Linux drawbacks:
- hardware compatibility (some hardware providers still ignore linux,
  and we had an issue with HP where nobody ever was able to say why
  the server kept rebooting sporadically without a clue)
- piracy (there are much less remote exploits for hp-ux than for linux,
  and hardware complexity/difference limits hacking possibilities)
- stability (ever seen a server with a load of 250 ? hp-ux can do it)

hp-ux advantages:
- stability (no I won't rewrite my sentence from above)
- hardware compatibility (ever seen an x25 comm card for linux ?)
- hardware standardisation (well, PA Risc hardware can only be shipped
  by hp, so there are less problems)
- software standardisation (even if conforming more or less to the
  systemV principles, SAM (system admin manager) is a nice tool for
  beginner sysadmins that don't want to mess with the system. Reminds
  me the day I blew up the apache config with linuxconf ...)
- it runs on a XCPU & YGb Ram machine (pick X & Y as you please), sends
  an e-mail if a blower fails, had LVM embedded many years ago ...

hp-ux drawbacks:
- where the heck have they put iptables ? (I wish they had an
  integrated firewalling software)
- you're looking for 'ping' ? here it is : -> /etc/ping (no, it is not
  a joke, it's the standard path on hp-ux 10/11 for the ping binary)
- the software management tool is great (it just has no dependency
  checking, ok, I am a SlackwareLinux fan, but that one is free)

aix advantages:
- hey, this is IBM stuff, can't be bad !

aix drawbacks:
- if your x25 calling number is odd, your call will not reach the
  remote device. the guy who developped this ? is in malaysia, and
  no, there is no backup for that precise piece of software. (no
  kidding again, this IS what happened to us)
- wasn't there an easy command line to list jobs of a printing queue ?
  on other unices I type "lpstat -o", but on aix well, it was something
  at least 30 chars long (ok, I could have remapped all the commands
  with shell scripts)

As I said, things surely have evolved, but so has Linux !!!
Now, you have high-end support, well trained and confirmed techies and
sysadmins, interoperability is not an issue, ... 

There must be other points, I'll write again if I remember them ...

Bye,

R. Daneel Olivaw,
The Human Robot Inside.