Sizing Guide Exchange Server 2003 - Fujitsu

White Paper Sizing Guide Exchange Server 2003 Version: 4.2, July 2006
Storage space
Now that we have intensively discussed the various types and performance of the individual components of
the disk subsystem, a significant question still remains: How much storage space do I need for how many
users? This results again in the classic problem of user behavior. Are all mails administered centrally by the
users on the Exchange server or locally in private stores (PST) under Outlook? How large are the individual
mails typically? Yes, even the client used, Outlook, Outlook-Express, or web-based access through a web
browser influences the storage space required by the Exchange server.
If the customer has made no specifications, it is possible to take a moderately active Outlook user who is not
idle and who administers his mails on the Exchange server as a basis. In this respect, 100 MB per user or
mailbox is very practical value. If your calculation adds a further 100% as space for growth and Exchange
has adequate working scope, this is then a very good value. The table shows disk requirement for the
database. In the calculation it has to be taken into consideration that a 36 GB disk only has a net capacity of
34 GB. And accordingly 68 GB net for 73 GB, 136 GB for the 146 GB, and 286 GB for the 300 GB disk. In
the RAID 5 calculation a package size of max. 7 disks was taken as a basis. From a performance point of
view it would be
advisable to choose a
package size of 4 or
5. In this respect, the
hard disk requirement
increases by 6 or
11%. As already
mentioned, RAID 5
should be avoided
with from a performance
viewpoint and
preference given to a
RAID 1+0 array.
User with
100 MB
Mailbox
In addition to the hard disks for the database(s) with the user mailboxes, disk requirements for public folders
must also be taken into consideration.
Moreover, hard disks are still required for
the log files. The scope of the log files
depends on the one hand on user
activity and on the other hand on backup
cycles. After a backup the log files are
deleted. A RAID 1 or RAID 1+0 should
be used for the log files. The table
opposite shows the disk requirements for
a log file size of 6 MB per user for three
days‟ storage.
In addition to the disk requirements for
the database and log files, Exchange still
GB
net
Logs per user
and day [MB]
Number of Disks RAID 1+0 Number of Disks RAID 5
36 GB 73 GB 146 GB 300 GB 36 GB 73 GB 146 GB 300 GB
50 10 2 2 2 2 3 3 3 3
100 20 2 2 2 2 3 3 3 3
500 100 6 4 2 2 4 3 3 3
1000 200 12 6 4 2 7 4 3 3
2000 400 24 12 6 4 14 7 4 3
3000 600 36 18 10 6 20 11 6 3
4000 800 48 24 12 6 28 14 7 4
5000 1000 60 30 16 8 35 18 10 5
Number
of days
6 3
Number
of users
Logfile
GB net
Number of Disks
RAID 1+0
36 GB 73 GB 146 GB
50 1 2 2 2
100 2 2 2 2
500 9 2 2 2
1000 18 2 2 2
2000 36 4 2 2
3000 54 4 2 2
4000 72 6 4 2
5000 90 6 4 2
needs storage space for queues. Queues can occur when mails cannot be immediately delivered, e.g. when
other mail servers cannot be reached or a database is off-line because of a restore. Queues are typically
written and read on a sequential basis. Separate storage space should also be provided for this. The data
volume can be estimated analog to log file requirements from the average mail volume per user and the
anticipated maximum downtime of the components causing the queue.
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