Server sizing; are there any standard guideline available

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blason
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Server sizing; are there any standard guideline available

Postby blason » Sun Dec 02, 2012 6:08 am

Hi Team,
I am trying to setup Email server for around 1000 users. So looking for any server sizing document for that. Or rather Please let me know if I am correct here and which topology woudl you suggest
First,
Trying to build one server with 24 GB of RAM which will have all the components installed on same server, will this suffice the need and can produce the optimized result?
Second.

Planning for distributed set up where I'll dedicated zimbra-mta for Incoming and Outgoing server and LDAP, MBX will be on other server. So total I will be having 3 servers for distributing load.
mxin.example .com = RAM 4 GB RAM

mxout.example.com = RAM 4 GB RAM

mbx.example.com/LDAP = RAM 16 Gb
Please advise.
Also what can be planned for secondary MX server


kruon
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Server sizing; are there any standard guideline available

Postby kruon » Sun Dec 02, 2012 5:31 pm

[quote user="blason"].. for around 1000 users. First,

Trying to build one server with 24 GB of RAM which will have all the components installed on same server, will this suffice the need and can produce the optimized result?[/quote]
You need about 50-150mb/user memory for logged in users, meaning in theory if you assume only 33% of your users are online at anytime 24Gb would be enough. 24/330 -> 73Mb

It would likely be slow to use.

I wouldn't try under 48Gb for 1000 users on a single server. RAM is cheap.

GB/user ratio should stay above 0,1, aim for 0,2+ so you'll have some room to expand.
[quote]

Second.

Planning for distributed set up where I'll dedicated zimbra-mta for Incoming and Outgoing server and LDAP, MBX will be on other server. So total I will be having 3 servers for distributing load.
mxin.example .com = RAM 4 GB RAM

mxout.example.com = RAM 4 GB RAM

mbx.example.com/LDAP = RAM 16 Gb
Please advise.[/QUOTE]
This sounds more sane. You don't need separate mxin,mxout. You need 3+ servers though



  • Directory server (ldap) acts as your master data which tells your other servers what settings are/if users exist/what groups exist/etc

  • mailbox server, which actually hosts the data, I'd split users roughly 200/mailbox server depending on quota needs

  • MTA server which handles inbound/outbound mail


Place 4-8Gb for LDAP, might be overkill, but just to be on safe side. I would use SSD here, maybe raid-1.

Mailbox server needs ram, it'll eat it like a lamb eats grass. I'd say 16Gb, 32Gb if you can spare it. Regular HDDs here since you're looking at large volumes.

SAN for mailbox use might be something you'd have to consider if you are planning +10Gb mailbox quotas.

MTA server memory requirement really depends on your actual mail volume, as AV scanning uses most of it, 4-8Gb should work. Regular HDDs as well, no need for massive capacity nor speed.
[quote]Also what can be planned for secondary MX server[/QUOTE]
I use simple postfix machine as secondary mx. It has postmap of approved email addresses for which it'll buffer/relay mail for, assuming the mail passes spam filters.

It will not provide users email access if my zimbra setup is down.
If you want more, you have 3 things to replicate(LDAP,mailbox,MTA).

You can search the forum for cold/warm standby for ideas how to run a replica system, but that basically will double your hardware cost.
blason
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Server sizing; are there any standard guideline available

Postby blason » Sun Dec 02, 2012 10:21 pm

so Kruon, 50/150mb/user is when user is using Webmail or Zimbra Desktop? Because I believe at that time maximum RAM will be utilized. is it not?

What if I am gonna use only IMAP/POP. I don't think that much RAM is needed for each user.
Also, how much CPU overhead it would have if IMAPS is used instead of IMAP? Would that make impact on RAM as well?

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