For Environment, a hotel is better than thousand cottages
Business rocks on mainframe part 3/6 – What are the key differences of distributed and mainframe environments? As a devoted spokesperson for Mainframe, let me present this through a somewhat exaggerated comparison.
Think of mainframe as a huge virtual hotel for thousands of guests. And a distributed environment as huge cottage village with a dedicated small cottage for each guest that you are managing.
In the virtual hotel the guests are happy, and the staff managing the hotel is relaxed, proud, and they have time to proactively solve the guests’ needs in advance. Everything is under control.
In the cottage village, guests are constantly looking for a better alternative to stay overnight, and the staff is reactively trying to solve all emerging issues as they would be first of a kind. New cottages are being built up each time a new guest pops up. Ok, there are now some modern cottages which can accommodate more than one guest per cottage, but still the landscape is not changing much from it.
Now, from the management point of view, would you prefer to be in charge of the virtual hotel or almost unlimited amount of small cottages?
In IT terms, the most obvious difference is the number of boxes and extra overhead like cables, data center facilities, security layers, software licenses etc. built around them.
Distributed environment - the cottage village
For a distributed server to be effective, it normally runs dedicated workload, and it has connections to all other servers participating in the business transaction. Some complexity will be added with security, backup, disaster recovery and virtualization, for each of the servers.
If you need more resources, you buy another box, or you add virtual resources to the system until physical limitations force you to buy another box. At some point, you end up with another box with connections to all other servers participating to the business transaction, and you add complexity with security, backup, disaster recovery, and virtualization. No matter if you take the servers from Cloud, from your service provider or from your own capacity pool, the underlying structure gets harder to control.
After a while you will be an owner of a server farm, and you need to have control over it. Updates to physical machines, operating systems, applications, javas, securities, connections, backups, disaster recoveries, virtualizations...
How many people do you need? How many processes? How many projects? How much money for just trying to keep everything under control…?
Mainframe - the virtual hotel
Mainframe, or z System as they call it nowadays, is built up to serve tons of various workloads at the same time. z System consists of Logical Partitions (LPARs), which are virtual machines inside the physical box. They run open Linux or z/OS as an operating system. z System has essentially been a Cloud for decades already before they even discovered the name ‘Cloud’ on distributed side.
Each LPAR can house hundreds of address spaces (with z/OS) or hundreds of Linuxes, and one address space under z/OS can do more work than any distributed server you can buy.
Since address spaces are all in the same LPAR, they can work effectively together without external connections among them. This is also true with Linuxes in their LPAR. They share same hardware, security, virtual and physical network interfaces, I/O channels, memory, operating system, applications, java, backups and their disaster recovery can be easily defined and maintained. And you do not need firewall definitions between them.
z/OS LPARs can further be combined as SYSPLEXes, which have high speed links between physical machines normally on separate datacenters. This approach gives you a possibility of zero downtime even if another datacenter goes down. Linux LPARs have similar possibilities with Live Guest Relocation to another available LPAR in same or in another physical machine.
z/OS SYSPLEXes can be controlled as one entity and they can distribute load between their member LPARs based on response time.
Cottages are good places to be at, once in a while
Even if I enjoy the cottage life in our beautiful Finnish nature - especially those warm summer evenings with sauna, lake and a cold drink in my hand - I just cannot lock myself or my customers in the cottage setting all year round. Distributed servers have their purpose, but relying totally on them is not always the best move. Why make life harder than it needs to be?
Now when we have a great opportunity to leverage the ‘best-of-the-best’ platform with Linux for distributed workloads as well, why not benefit from it?
You can easily build up your own virtual hotel for the large part of your IT workload, and leave the rest in your nice little cottages - but so that it is a pleasure rather than a burden to have them.
And remember, that there is always the option to leave it all for a professional partner like Tieto to manage and deliver the services from the cloud.
Be smart about how to spend your time, money and energy and make sure you find the way that serves you best in the long run!
If you liked this post, stay tuned. In the next post I will reveal some facts why the virtual hotel is as powerful as it is.
See my previous blogs: How to minimise IT downtime and maximise customer satisfaction? and Want to be free from security stress?