1. Unix Server Consolidation
Andrew Moss
Midrange Design Engineering – Design and Integration

2. Introduction
This presentation provides an overview of some of the benefits that CSC and our clients would derive from server consolidation.
The presentation describes the business benefits expected from server consolidation, and attempts to examine some common approaches and their benefits and limitations.

3. Types of Consolidation
There are a number of approaches that can be taken to consolidate Unix/Linux services
OS Instance consolidation
Server consolidation on to large servers running multiple OS instances using hardware or software OS partitioning
Consolidation using 3rd party virtualisation software – for example VMware for Linux
Application Consolidation
Reducing the number of applications
Running compatible applications on a single server
Use of resource management to create a degree of application isolation

4. Drivers for Consolidation
It is important to understand what the drivers for consolidation are, and what business benefits we are trying to obtain. Some of the reasons for consolidation are listed below
Reduce number of applications
Remove old hardware/software versions
Decrease software and hardware maintenance costs
Reduce power and footprint requirements
Reduce the number of OS instances to be managed
Provide flexibility in provisioning resources
Tidy up existing environments that may not have been well designed or implemented
Increase understanding of environments that have grown over many years and may not be well understood
Add functionality – for example ease of DR and Backup

5. OS Instance consolidation
Consolidation of many OS instances onto a single server provides a number of advantages
Much improved hardware utilisation
Removal of outdated hardware
Decreased hardware and software maintenance costs
Reduced power and cooling requirements
Upgrade of OS version
Increased flexibility in provisioning
Less hardware to recover during a DR situation

6. OS Instance consolidation
OS instance consolidation alone however does not address many of our identified business drivers for consolidation, and actually adds cost and complexity in some areas
Does nothing to reduce number of applications
Does not reduce the number of OS instances to be managed
May require newer OS versions that do not support current applications
Does little to tidy up existing environments that may not have been well designed or implemented ( other than improved OS currency )
Does nothing to improve the number of applications that have to be recovered in a DR situation - creation of partitions / virtualisation layer may actually increase the time to recover vital services
Virtualisation/partitioning technologies add cost, complexity and administrative overhead for the system administrator. There is also a performance overhead.
Where larger servers are deployed there is a per CPU cost premium over smaller servers ( See backup slides )
Failure of a single server results in bigger impact to business, may be addressed by HA clustering but this adds system administration complexity
Maintenance requires agreement from more business units

7. Consolidation – Decrease number of Applications
Consolidation by decreasing the number of applications has the potential to bring a lot more advantages
Reduced number of applications removes cost and complexity from the environment
Removal of older applications removes dependencies – for example old application versions may not run on new OS/Hardware
Simplification of the application environment removes clashes between applications and therefore allows a reduction in the number of OS instances to be managed
Drive utilisation of servers by consolidating functionality on to a smaller number of servers
Often allows improved business processes to be developed
A reduction in the number of applications has a major impact on ease of DR, and ease of management

8. Consolidation – Decrease number of Applications
Consolidation by decreasing the number of applications however is not initially a low cost option
Can be very disruptive to client business during transition
Requires input from client to define business processes
May not be an option where historical data prevents removal of an application

9. Consolidate existing applications onto less OS instances
Running multiple existing applications on a reduced number of OS instances provides a number of advantages
No need for business changes to consolidate applications
Drives server utilisation
Reduces OS management overhead
However it also brings a number of risks
Possible incompatibilities between applications – different applications may require specific versions or modifications to the OS
Applications may impact each others performance
Security boundaries between applications are removed
Failure of a single server results in bigger impact to business, may be addressed by HA clustering but this adds system administration complexity
Maintenance requires agreement from more business units

10. Consolidate existing applications onto less OS instances – With resource management
Introducing resource management addresses some of the issues
Provides guaranteed levels of performance to individual applications
Newer functionality such as Solaris Zones also provides a degree of fault isolation and name space ( security ) isolation.
Resource management and Zones have some limitations
Often requires newer OS versions – existing applications may not be certified or may not run at all on newer versions
Can impact application functionality
Increased system management effort required to configure
Adds complexity, for example when fault finding
Not available on some flavours of Unix and Linux
May not be fully supported by infrastructure tools yet, for example backup products

11. Summary
A combination of OS and application consolidation is required to gain all of the business benefits promised by consolidation.
Many technologies will increase system management overhead and add cost and complexity in some areas – this increase in complexity has to be balanced against other benefits for example reduced maintenance, footprint, power, hardware costs and flexibility.
Care is needed to target the most cost effective solution at the individual business problem – large partitioned or virtualised servers may not be the answer where workload is predictable and flexibility is not required.
Consolidation of many services onto a single server also means that areas such as High Availability that were not a consideration before, may become important.

12. Backup Slides

13. Does it always make sense to virtualise ?
One of the drivers to virtualise is to improve utilisation, However the table to the right shows that the cost of a CPU increases dramatically as you purchase larger servers …..
For example we have 4 workloads that vary between 4 and 8 CPU’s. The maximum CPU requirement is 32 CPUs. We could host this on a 24 way E6800 and assume that we will save 8 CPUs on average. However if we bought 4 8 way V880s they would cost $343, Still a saving of $1/2 Million dollars on purchase price.
Although this is an extreme example, similar situations will apply in the low end space – with solutions such as VMware we also need to allow for software license costs.
Virtualisation often makes most sense where workload is unpredictable, or when workload does not map well to CPU boundaries
CPU’s
Sun
List
$ per CPU
Relative 1
V120
$1,995
1.0 2
V240
$6,495
$3,247
1.6 4
V440
$15,995
$3,998
2.0 8
V880
$85,995
$10,749
5.4 24
E6800
$842,895
$35,120
17.6 36
E12K
$1,389,330
$38,592
19.3 We
Information extracted from CSC RDC overview
Prices are indicative list prices taken from Sun web site
Similar trends from other vendors (this is not Sun specific)
Very simplified comparison based on acquisition price only
No discounting applied
Not a TCO comparison
But serves to illustrate the point!
Try this out with your own preferred vendor and discounting

14. Links to other useful information
The following documents created by Midrange DE D&I may be useful
Quick Overviews
Unix Server Virtualisation Overview
Solaris Zones / Containers Overview
Detailed Presentations
Unix Partitioning and Virtualisation technologies Presentation
Solaris Containers Overview and Configuration Guide
IBM Power 5 Overview
IBM Power 5 Virtual IO Server Configuration