Kielek is correct, but consider this.
1. Given the availability of the application, there is a small difference
between Linux on z and Linux on Intel simply because the zSeries
reliability takes the hardware multiplier on availability closer to 1.
2. Yes we can configure the Intel with redundant servers to mitigate the
reliability difference.
a. In the case of stateful applications such failovers are small
outages because they take measurable time (up to minutes or even hours on
thorny situations). In this case the reduction of the number outages by
better hardware availability still helps.
b. In the case of stateless applications you need less redundant
hardware on z than on intel because you can effectively run the z at higher
utilization than the intel machine for many applications. This is because
many workloads cause the Intel boxes to saturate a relatively low
utilization. When this happens it takes more than n+1 boxes to deliver
n+1 availability is > than one unless the Intel machine is run at very low
utilization. Since the zSeries solution is more like to be CPU bound the
utilization at which n+1 can be n+1 is higher.
c.) Since the failing component is most likely the application or the
linux, there is the opportunity to set the Linux on z farm up in such a
way that the remaining linux images get the capacity that the failed linux
had. In other words a redundant linux/application instance is provided but
still less redundant capacity is required. This depends on being able to
detect the failure and restart the failed linux with reduced resources
until it is ready to accept the load.
That is the failed linux gets hard capped and the remaining soft capped
images grab the resulting whitespace.
Joe Temple
Executive Architect
Sr. Certified IT Specialist
[EMAIL PROTECTED]
845-435-6301 295/6301 cell 914-706-5211
Home office 845-338-1448 Home 845-338-8794
"Kielek, Samuel"
<[EMAIL PROTECTED]
rriott.com> To
Sent by: Linux on [email protected]
390 Port cc
<[EMAIL PROTECTED]
IST.EDU> Subject
Re: Why Zseries
02/10/2005 01:46
PM
Please respond to
Linux on 390 Port
It is important to also understand that Linux is not capable (at least
today) of directly exploiting many of those hardware benefits,
especially in terms of the mainframes RAS features. That is to say,
there can be instances where the mainframe is up and chugging along, VM
is doing just fine, but Linux is dead in the water for example.
Unfortunately the original question is simply too vague. Comparing Linux
on zSeries to x86, pSeries, SPARC, etc. (if that was question) is as
much a philosophical exercise as it is technical. What really needs to
be focused on is the task that you wish to run, how it works and what it
needs to perform its job(s). Then we can evaluate the pros and cons to
running that task on each of the OS/architecture combinations.
-Sam
-----Original Message-----
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of
Adam Thornton
Sent: Thursday, February 10, 2005 12:39 PM
To: [email protected]
Subject: Re: Why Zseries
On Feb 10, 2005, at 10:58 AM, Levy, Alan wrote:
> Actually, I probably phrased my question wrong.
>
> What I was looking for is why choose Zseries Linux over ANY OTHER
> operating system's Linux ?
>
We're getting closer, but:
zSeries is an architecture, not an operating system, and Linux doesn't
generally run *on* an operating system[0], it *is* an operating system.
That said, this looks like Question 2, if you substitute
"architecture's" for "operating system's". In which case: hardware
reliability and fault tolerance, excellent sustained I/O capacity,
potential for in-the-box really-high-speed interconnect with (usually
z/OS) big databases in another LPAR, humongous consolidation
opportunities if you have lightly-loaded guests, and incredibly rapid
deployment of machines for testing and development.
Adam
[0] Unless run in a virtualization environment, like z/VM or VMware or
Virtual PC, or Hercules, which is an emulation environment running
under some OS.
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