I hope first
Part of this series was informative and it may help you at some degree. In this
post I am going to discuss about Virtual Host Sizing. You can find tons of
information on this topic on Web however what I really don’t find is the
consolidated view/approach. I am going to make this as simple as possible and
hope this may help you.
Having said
that, let’s get started. First of all you need to know what are the
pre-requisites before you start sizing for Virtual Hosts.
·
Pre-requisites
Identify
workloads/Servers which can be virtualized.
Peak
Hour/Average resource usage (CPU/Memory/Network/Disk).
Resource
usage report for 1 Month at least.
Consolidation
ratio (How many servers are going to share the Hardware)
Ad-hoc
capacity demand
Well there
may be several other factors to consider which I am going talk about later in
this post.
So how to
know what may be/ may not be virtualized, what is the current/peak hour utilization
& Average utilization for the period of time. Let’s talk about it one by one.
What
can be virtualized: - Tons of case studies and guidelines are available on web
from VMware/Microsoft/Citrix etc. Question is , is there any thump rule which
can help me to categories workload which are potential candidates for
virtualization even when I don’t have utilization report with me ? Yes… there
is… some of them are
§
Infrastructure
servers (AD, DNS, DHCP, Print Server, File Servers etc.)
§
Web
Servers or Intranet Portal Servers
§
Utility
Servers (WDS, AV Distribution Points, SCCM Distribution Points, Altiris
Distribution Point, WSUS etc.)
§
Middleware
Servers
Alright,
what about other servers like (Application Server, DB Server, and Messaging
& Collaboration Server etc.) Well that’s where you need do utilization
analysis. Now the challenge is, how do I get utilization report from 1000s of
servers spread across multiple location ? Well then you need to think about
some automated tool & Solution which can do this work for you. Let’s talk
about them. These tools are smart and will tell you which workload is good or
bad for virtualization.
Ø
Microsoft
MAP Tool Kit:- Microsoft Assessment & Planning tool can help you to
discover and collect performance/resource utilization from multiple servers.
Ø
VMware
Capacity Planner: - Well, I am not big Fan of Capacity Planner because you rely
on VMware to do Analysis for you and publish report on the Dashboard. But many
of you would like it.
Ø
Platespin
Recon: - Excellent tool for Analysis and reporting, I prefer using Recon.
Ø
IBM
cDAT :- Although I have not used it but I have heard good feedback for this
product. Worth trying it…
You
may find some other tools/solution on web however I may not comment on those as
I have not used them.
Alright,
so what Next… Well now you have complete Data to process and make a decision on
size. If Data collection and analysis
was properly done you should have following Data with you.
Ø
Total
Number of servers which can be virtualized
Ø
Total
CPUs allocation and actual usage on servers which are identified as virtual
candidates.
Ø
Total
RAM Allocation and actual usage
Ø
Disk
Size on Servers (SAN/DAS)
Ø
IOPS
Ø
Network
Bandwidth usage
So let’s put
some data and try to understand by example.
Ø
Total
Number of servers which can be virtualized - Assume 100
Ø
Total
CPUs allocation and actual usage on servers which are identified as virtual
candidates – 200 Cores (Assuming 2 Core per server)
Ø
Total
RAM Allocation and actual usage – 1600 GB (Assuming 16GB per server)
Ø
Disk
Size on Servers (SAN/DAS) – 6000GB (Assuming 60GB per server)
Ø
Network
Bandwidth usage – (10000 MBPS, 100 MBPS per server)
Ø
Consolidation
Ratio = 1:10 (Just an example)
So
for 10 virtual Machine the total capacity I need is as follows
Ø
CPU
2x10 = 20 Cores (Sizing on actuals , in real world although server has 2 cores
allocated to it but peak hour utilization is just 1 cores of even half)
Ø
RAM
16GB x 10 = 160GB (Again you need to
look at peak Hour utilization and adjust it accordingly with some buffer)
Ø
Disk
60x10 = 600GB (put some buffer for Page file & Swap space
Ø
Network
100x10 = 1000MBPS (Gig Adapter)
Having
said that, the size of the Box will be
CPU
= 2 Socket - (16 Core each)
RAM = 164GB
Disk = 600GB (Add buffer)
NIC = Dual Port 1gig
And
then add 10/20 % Extra capacity for sudden burst depending on your budget and
do think about Hypervisor penalties (Hyper-v guys would know what I am talking aboutJ)
When
you are planning for HA or on demand provisioning you need to think about
failover and spare capacity as well.
This
topic is really huge and you can hear lot of debates on sizing but I believe
this post can help you to some extent.
I
will talk about some of the other factors to consider in upcoming post on virtualization
planning…
Wish
you all good weekend!!!
Cheers!!
Pankaj
keep em coming
ReplyDelete