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Grinsell, Don wrote:
> their biggest concern is that Linux isn't
> AIX:

This is really a social and comfort question, and not a technical one.
 Unfortunately, you can't really answer those.  These admins are
basically saying they will move or not move based on their feelings
and impressions.  The only real answer to that is hire extra admins,
ones familiar with linux, who can work with the existing ones to get
their comfort level up.

That said, here's a few answers from my perspective, based on our
experience running 140 combined distributed intel and virtual zlinux
instances, and about 200 aix lpars.

>
> "In my opinion, and the last time I talked to him, admin x agreed with
> me, Linux is where AIX was ten years ago.  It does not have the
> management tools,

Management tools to do what?  As far as i can see, YaST does all the
same tasks smitty does.  AIX may have mkuser, linux has useradd.  You
say tom*A*to, I say tom*a*to.  Just another set of tools to get used to.

I find some things significantly easier to do on linux than on AIX.
Making a box into a LDAP client using TLS on the wire, for instance.
AIX doesn't even support using anonymous access to LDAP, and my memory
is fuzzy, but I don't think it does TLS, either, instead requiring the
not really a standard ldaps (port 636) ldap over ssl.

For heavens sake, the AIX ldap client wants to be configured with a
LDAP administrator account with full privs to modify the repository!
Hello!  Can you say gapingly bad design?  What if I want my clients to
work off of one of several read only LDAP replicas?  What if I don't
want a local AIX security compromise to mean my entire LDAP repository
is also compromised?

Another example is managing a shared, platform heterogeneous
distributed printer database.  Linux LPRng software from the
distributors works out of the box, simply by copying a common printcap
around.  We have to compile and support LPRng for AIX ourselves, and
disable the native qconfig.  We could copy qconfig files between AIX
boxes, but certainly not to any non-AIX platform like solaris, hp-ux,
or linux.

> has not proven itself to be as stable,

According to our support tickets filed to IBM, Redhat, and SuSE, AIX
has actually had more problems per machine than Linux.  <sarcasm> Does
this mean that AIX is less stable than linux? </sarcasm>  This is
simple lack of understanding and discomfort.

> and has not
> earned the level of trust that AIX has.

Translated: I haven't run it.

> Trouble-shooting and reporting
> tools are primitive.

This is a the first real point given, at least as far as diagnosing
kernel issues.  In our experience, it hasn't been a deal killer, but
other's experience may differ.

> We are running it today in a few limited
> instances, and it has its gotchas, like needing down time to add disk
> space to file systems.

This, I fear, is simply wrong, on both distributed intel and virtual
zLinux.  I add san luns / dasd and grow LVM volumes and ext3
filesystems online all the time, and have for several years.  It is
true that you cannot *shrink* filesystems online.

> Ten years ago, AIX was the same way, but it has
> matured a lot - Linux still has a long way to go.

There are, in fact, features in linux that are not as mature as AIX.
Software volume mirroring, for example.   However, the arguments these
admins gave you only mentioned one of them.

Now there *are* real drawbacks to running virtual anything on z,
compared to running dedicated on Power LPARs, but they are more
related to distributed vrs virtual than to the two OS's involved.
You'd face the same drawbacks if there were an AIX than ran on z/VM,
being compared to linux on power.

For example, updating the system on a z series (e.g. upgrading z/VM)
requires an outage of *all* the linux guests hosted there.  This is in
addition to bearing the cost of upgrading a linux guest (e.g. from
SuSE 9 to SuSE 10) effecting the individual guest.

Upgrading AIX on an LPAR effects only that one AIX instance.

Obviously, also, running a virtual machine for something that needs
any significant CPU horsepower is contra-indicated.  Also, if there's
 requirements for certain types of dedicated bandwidth (e.g. needing 4
bonded gigE's for a very high throughput file or backup server) you
might as well do it on a distributed platform.

Others have already talked about virtualization's advantages.

> Several years ago,
> admin x was troubleshooting AIX and had IBM support on the phone.  The
> IBMer told him to type in a data collection command, and the command
> knocked the system down.  Today it doesn't.  That is the same type of
> maturing that Linux is still going through.

Apologies, this doesn't make sense ... I killed an AIX box long long
ago, thus something completely unrelated to AIX must also be bad?

I think this is another argument stemming from impressions, rather
than technical realities.

> It doesn't matter whether
> it is on the mainframe or on an Intel server - you don't want to trust
> Linux with mission critical jobs.

Okay.  A few of our mission critical apps on linux:

* DNS

* LDAP Authentication / Directory service

* Internal search engines (critical for our hospital nursing staff to
find treatment info for medications)

* Global systems monitor (tivoli / omegamon)

* Tandem SQL database virtual tape backup systems.  If this doesn't
work, the clinical app's tandem databases stop transactions, because
the database logs fill.

* Medical transcriptionist's document coding

* (Of course) mayoclinic.org web servers

> We can run it, as long as we are
> willing to accept the outages that are normal to any immature
> technology.  Apps like Service Center come to mind, because not many
> people consider it a crisis when that is down."

Really, it's a comfort level thing.  You *can* run critical apps on
linux.  You can find/install (open source) or buy the management
tools.  You can get the HA/Enterprise clustering (Redhat Cluster/GFS ;
Symantec / Veritas clustering).  You can run it on hardware of the
highest quality and availability (zSeries / IBM Power)

None of this, though, will matter.  This is an emotional argument, not
a technical one.  I fear you may end up doing this with only the
grudging support of your admins, until when and if their impressions
change.

Regardless, good luck.

- -- Pat

ps.  if it'd help, I'd gladly do a conference call to your admins, and
share my impressions from a mixed shop with them.
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