Re: Is an IBM pSeries 615 a good deal?
From: Dan Foster (dsf_at_globalcrossing.net)
Date: 01/02/04
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Date: Fri, 2 Jan 2004 05:33:40 +0000 (UTC)
In article <3d6111f1.0401012037.60f0d731@posting.google.com>, Mike Cox <mikecoxlinux@yahoo.com> wrote:
> Hi. I'm looking at purchasing an IBM pSeries 615 server, and am
> wondering how it compares to Intel/Linux. I have no pSeries/AIX
> experience, only Linux and AMD/Intel.
First, a disclaimer -- I have worked with Linux personally in 1993, in an
all-Linux shop in 1994-1996, and still run Linux at home and work
(production servers and desktop workstations), although current employer is
big on both AIX and Solaris which accounts for about literally 98% of all
servers that my team manages.
I also have no affiliation with any server vendor other than as a satisfied
customer or someone who has done extensive research.
> My question are:
> is the Power4+ processor up to par with Intel performance (Xeons)
Heh, you should reask that question as: "Are the Xeons up to par with
POWER4 performance?".
In short, POWER4 blows most everything away -- scalable to 32 way easily,
an unbelievable amount of RAM, with a nice CPU cache design and on-chip
high speed access, along with underlying logical partitions support and
related hardware RAS (reliability, availability, serviceability) features.
In fact, the POWER4 is one of the top selling processor in its class vs the
DEC/HP/Compaq Alpha (pretty darned good chip!) and the Sun UltraSPARC
(pretty decent too for the III series, which is the direct POWER4
competitor) amongst others.
If you have applications that takes advantage of the POWER4 architecture
one way or another, they'll probably exceed your wildest dreams. If you've
got applications that don't really take advantage of anything architecture
specific, then you could potentially be better off with a cheaper x86
server.
> is AIX better than Linux in terms of features and stability
Lots. For one thing, IBM doesn't drastically change the internal API once
every 12 months or so :-) They identified that as being one of the
important factors to third party device driver writers.
However, there is a tradeoff... stability comes through discipline and
control; so IBM doesn't have as many devices supported due to lack of
driver support as compared to Linux. Implications? You're wedded to IBM
sold (or resold) gear if you go in that direction due to the device driver
support rather than being able to buy commodity off-the-shelf part, throw
it in, and expect there to be an existing OS device driver for it.
On the other hand, AIX supports far more enterprise class features such as
management, monitoring, reliability, disk management, etc, all out of the
box. I can't even run a LVM on my FreeBSD box because vinum is flaky, but
no worries about that whatsoever on my AIX boxes even dating to my first
AIX machines in 1996 running 4.0.4. (In that time, I have run into only one
LVM bug which I reported -- and was fixed about 8 hours later by IBM's
level 3 support; when I woke up, I had an efix ready to apply which fixed
the bug until the next fileset update came out.)
Linux is great stuff... I'm one of the people supporting it for my
employer, for myself, and for my friends in the past decade... but in a
commercial shop, if you run into a kernel bug that is gumming up the works
and you need a fix *now*... you may not have the luxury of time of waiting
and hoping that someone else issues a patch unless you're seriously good
and can do kernel level or device driver hacking on your own.
What IBM provides is an existing support structure that can produce results
fairly quickly with a talented base of experts ready to jump on problems.
Be it hardware or software.
> and can I use exisiting Linux apps in AIX with only a recompile?
Well, that depends. :)
For the sheer majority of open source software I've ever built (mutt,
ncftp, fetchmail, elm, INN, GD.pm, perl, whatever... you name it), it
builds out of the box under AIX.
An AIX newbie of a co-worker didn't believe that so he got assigned a
project to build about 90 tools for a new AIX shell server... at the end of
the project, he sheepishly admitted he was able to build all but about 3 or
4 'out of the box' and got the last few to build by minor edits (eg
'sys/select.h' rather than 'select.h').
If you have something that is truly unique to Linux that does not
ordinarily build under any other UNIX platform (these are *extremely* rare;
only about two or three such packages I've ever seen in the last 8 years),
then the ability to recompile under AIX may depend on *how* Linux-specific
its stuff is -- ie, does it take advantage of undocumented ioctl or kernel
features?
AIX also provides support for a number of other enterprise software add-ons
such as a mature clustering product, for one. (We use it here; HACMP.)
Vendors are more willing to target something that isn't as much of a major
moving target.
For instance, take Tivoli Storage Manager (TSM) which is the enterprise
software we use to run our backups -- it's the major competitor to Veritas
NetBackup (and to a lesser extent, Legato NetWorker).
TSM server can run under Windows, Linux, AIX, Solaris, HP/UX, OS/400, and a
few other platforms... we and some other sites looked at possibly running
TSM server under Linux due to the cheaper hardware costs.
We were a little disappointed with our testing because due to the inherent
existing design, TSM would only work with a *very* specific distribution
and more worrisome, with a _very_ specific kernel version. We tried even
one minor version above (ie, 2.4.20-6 vs -5) and it refused to load. Being
binary only, we didn't have any recompense. Also means if they find serious
security holes in the Linux kernel (as happened recently), requires an
immediate kernel upgrade to fix it... but in the process, break the major
apps like TSM.
TSM may be better and more flexible under Linux some day, but right now,
it's seamlessly integrated with AIX and Solaris (for instance).
> The reason I'm thinking of making the switch is because I need a
> vendor that will make a system that has all components Linux/Unix
> compatible. Too many times I've run into issues where there are no
> Linux drivers for my system. I'm looking to get rid of the x86
> hardware driver headaches so here I am. :-) I would prefer to run
> Linux on the pSeries if it is better and I need the following software
Well, 'is better' is really mostly subjective with some semblance of
objectivity. It ultimately depends on your overall goals.
> PostgreSQL (RDBMS)
> SuSE or Redhat Linux
> inn (news server)
> gcc and g++
> apache
> Mozilla
> KDE and Gnome
I've got all but the first two to build under AIX just fine. In fact, INN
was my very first project when I got hired by my current employer in '96.
Ran well on a machine far smaller than a p615, let's just say :-) Held up
well in brutal use in production with almost no downtime whatsoever due to
the nice LVM features (amongst other stuff). I'm sure PostgreSQL probably
builds fine; I just haven't personally done it.
'SuSE or Redhat Linux' -- that's a good question. IBM supports RH Linux on
its current pSeries servers (like the 615, I'd bet) but to do so would
exclude AIX and you'd probably be forever wedded to IBM for any RH patches
and whatnot unless you were willing to support bug fixes on your own.
> Does the pSeries offer anything more in terms of reliablity, data loss
> protection, than the generic x86?
Oh man... no offense, but don't even know where to start. :)
Chipkill for CPU and RAM, built-in hardware lights out management style
support (integrates into the PSU and all), predictive failure analysis for
hardware as well as drives, logical volume managers, a centralized error
reporting facility that the system and all apps uses (mainframe-ish but is
*extremely* handy in terms of day to day administration), and a lot other
hardware and software RAS features.
The list is sufficiently long enough that I would highly recommend you take
a look at the pSeries web site (www.ibm.com, select your country, enter
'pSeries' in search box, select the main hardware web site for pSeries,
look through the product listings like for the 615; one of the links there
will have a 'features / benefits' type document.
> This is what I'm looking at right now:
>
> http://www.ibm.com/eserver/p615
It's a pretty darned nice box. I should also mention that (some folks here
will hate hearing it) the Sun SunFire V210 or V240 is quite a bit cheaper
and seems to have much the same hardware features plus some beyond; of
course, they only run Solaris.
Ultimately, you may conclude that you would prefer to run with an IBM
xSeries (we have a few of them here, too) machines running x86 or Dell or
Compaq, but at least it sounds like you're making a serious effort to look
at all angles... software, hardware, present needs, future growth and
maintainability. I'm sure that whatever you eventually settle on will be
well matched to your specific needs given the amount of research and
consideration you're putting into all that.
-Dan
(posted to USENET and emailed as a courtesy.)
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