HP HOWTO: Configuration Guide and Use of HP Products under Linux (Version 0.94)
	Chapter 4. Solutions and Sizing

4.2. Internet/Intranet Linux server

4.2.1. Web Server

The Web service uses 2.5 MB of RAM, in static mode (simple HTML pages) and 5 MB of RAM in dynamic mode (HTML pages generated from perl, PHP, ...) per user. The disk space needed is function of the nature of the server, knowing that most of the consumption comes from images. Processor resources used are important, thus it could be useful to consider the increase in frequency and the addition of processors, because this type of traffic could be quite well done in parallel. With Apache 2.0 and the support of threads, it will become even more obvious. We will priviledge also the I/O speed with Ultra 2 LVD SCSI at 80 MB/s, if the budget allows it, and 10.000 RPM disks.

Table 4-3. Sizing of a static Web server

Simultaneous users	RAM size	Disk size	Machine example
1 - 100	256 MB	9 GB	E800
100 - 500	1 GB	9 GB	LC2000 Bi-processor
500 - 1000	2 GB	9 GB	LH6000 Quadri-processor

Table 4-4. Sizing of a dynamic Web server

Simultaneous users	RAM size	Disk size	Machine example
1 - 100	512 MB	9 GB	E800
100 - 500	2 GB	9 GB	LC2000 Bi-processor
500 - 1000	4 GB	18 GB	LH6000 Quadri-processor

4.2.2. Mail Server

Generally, this machine is used as both SMTP (sending and reception of messages) and POP/IMAP server (keeper of messages and manager of client accesses). The SMTP Mail service uses 2 MB of RAM per user. The POP/IMAP Mail service uses 2 MB of RAM per user. The disk space needed becomes more and more important as long as attachments (images, various documents) take the greatest place in exchanges via e-mail. We consider in that case that an average mail box size is 50 MB. Processor resources used are important, thus it could be useful to consider the increase in frequency and the addition of processors, because this type of traffic could be quite well done in parallel.

Table 4-5. Sizing of an e-mail server

Simultaneous users	RAM size	Disk size	Machine example
1 - 100	400 MB	9 GB	E800
100 - 500	2 GB	27 GB	LC2000 Bi-processor
500 - 1000	4 GB	54 GB	LH6000 Quadri-processor

4.2.3. Firewall/Proxy/Web-Cache server

Generally, this machine is both a Firewall server, a proxy (in both directions) and a cache for the Web because all requests go through it. The Firewall service uses 1 MB of RAM. The Proxy service uses 0.3 MB per incoming relay. The Web cache service uses 0.5 MB per user. The disk space needed is function of the parameters of the cache Web server. In that case, we consider 20 MB per user. Processor resources used are important, due to the analysis of IP packets. Thus it could be useful to consider the increase in frequency.

Table 4-6. Sizing of a Firewall/Proxy/Web-Cache server

Simultaneous users	RAM size	Disk size	Machine example
1 - 100	128 MB	9 GB	E800
100 - 500	512 MB	18 GB	E800
500 - 1000	1 GB	27 GB	E800

4.2.4. Directory server

Generally, this machine use a software like OpenLDAP to fulfill its goals. The LDAP service uses 1 MB of RAM and 10 kB of RAM per user. The disk space needed is of the same kind, so 10 kB per user. Processor resources used are moderated.

Table 4-7. Sizing of a LDAP server

Simultaneous users	RAM size	Disk size	Machine example
1 - 100	64 MB	9 GB	E800
100 - 500	64 MB	9 GB	E800
500 - 1000	128 MB	9 GB	E800