System Requirements - Small Systems

[dwmtractor]

I have ZCS 4.5.6 set up on an IBM x330, 1.4 GHz, 512MB, roughly 70GB hdds (a pair in RAID-1). According to the hardware requirements listed by Zimbra, this is too small, yet at the moment (about a dozen users, combination of IMAP and web but mostly IMAP) it seems to be performing quite well.

My question is what range of users to computing resources others have observed. I'm thinking as I bring the rest of my 30 users on board I want to at least move up to a gig of RAM, but I'm not even sure that's all that necessary.

The stuff I've seen on the boards so far is mostly for people using hundreds or thousands of users. Practically speaking, for those of us in the 25-50 or 50-100 user range, what sort of computing resources are

• required?
• recommended?
• known to work?
• known to bomb?
• maybe will work, but you'll be sorry?

[phoenix]

It all depends on their activity and usage of the system. If you're going to keep that system then I'd recommend more RAM, probably 2GB - it makes the system more responsive. For the hard drives a RAID10 is the preferred choice for performance but you probably don't need it.

[dwmtractor]

I agree, Bill, I'm a believer in RAID 10 but this particular chassis only holds two drive bays so it's not an option unless/until I change boxes!

RAM is cheap, tho, so I certainly don't have an issue with upgrading that.

Is there any indicator other than people bellyaching about slow performance (or not doing so) that will help me assess the RAM usage effectively?

Thanks

[dwmtractor]

Originally Posted by phoenix

It all depends on their activity and usage of the system. If you're going to keep that system then I'd recommend more RAM, probably 2GB - it makes the system more responsive.

When I set up Ubuntu I chose the default configuration for my /swap drive of about 3x my RAM, so it's roughly 1.4GB in size. Of course I used all the rest for /, which means I have nothing left. If I upgrade the RAM without also resizing the swap partition, am I going to ask for serious trouble? Either right away or over time?

Bottom line if the answer is "yes" is that I'll have to RE-Re-reinstall my Zimbra on a new Linux install but better partitioned. I'm not excited about doing that, but if I must, I must.

[mmorse]

See the swap file idea below-but first some thoughts:
Well that brings up the old swap should be = 2 x RAM rule of thumb...however, even upgrading to 1GB of ram your swap is still larger so your technically ok there.
Seriously, 2+Gb of ram and Zimbra will sail like a cruiser instead of a tin can frigate or a landing craft. Wish I knew where it was, didn't see it in the wiki, but someone had a guide to getting zimbra to work on less than 256mb; which may be fine for the home setup but wouldn't support many more users.

And the more ram you get-hopefully you will won't rely much on swap, though for a multitude of reasons it's a good idea to keep it at least = to the size of your installed ram.
If you go larger and still want to quell your worries-you can always add swap files.

Here, I even tracked down a ubuntu article for ya:

• Usually, people associate swap with a swap partition, maybe because they've been proposed to create a swap partition on install. In fact any file can be used as a swapping device, be it a partition or a conventional file.
• It's true that swapping to a real partition is faster than swapping to a file, but not that faster. If you're considering responsiveness, my advice: add more RAM. Swapping to a partition or a file won't change anything.
• Adding more swap is a four-step process :
  • a- Creating a file the size you want.
  • b- Formatting that file to create a swapping device.
  • c- Adding the swap to the running system.
  • d- Making the change permanent.

Whole thing here: https://help.ubuntu.com/community/Sw...ad0fc0596a9ba8

[mmorse]

Found it, 256MB - though he did sacrifice AS/AV & the logger service (well on a single server install he didn't need imap/pop proxy either obviously).
By no means the first, keeping in mind that the min requirements go up over time - ram sizes always appreciate (someone should have just called it 'YANMRAM' - you always need more RAM) but he did nicely document his steps:
Zimbra rocks

Also on:
Performance Tuning - ZimbraWiki > Moved > Making Zimbra run on minimal RAM - Zimbra :: Wiki
Originally from:
Zimbra on 256 MB ram at Code, the universe, and everything

[phoenix]

Originally Posted by dwmtractor

When I set up Ubuntu I chose the default configuration for my /swap drive of about 3x my RAM, so it's roughly 1.4GB in size. Of course I used all the rest for /, which means I have nothing left. If I upgrade the RAM without also resizing the swap partition, am I going to ask for serious trouble? Either right away or over time?

Bottom line if the answer is "yes" is that I'll have to RE-Re-reinstall my Zimbra on a new Linux install but better partitioned. I'm not excited about doing that, but if I must, I must.

A swap file is an option not a necessity - the more ram you have, the less likely you are to use swap. That is, of course, a generalisation but I would increase the RAM and monitor swap usage but you should find that 1.4GB swap is more than enough.

[mmorse]

Unless he puts in 8+GB and wants to allow that box to 'hibernate' -but I seriously doubt he plans to hibernate his mailserver
Which is why I said that if his monitoring discovers that it gets close: "If you go larger and still want to quell your worries-you can always add swap files." instead of just the partition area.

[wolrah]

I just have to say that if anyone is considering running a real (as in more than a toy) e-mail server with Zimbra, don't even consider less than 1GB RAM. With 15 active users I had a Athlon64 3200+/512MB box crying on its knees, swapping like crazy, and regularly dropping services (particularly logger and mailbox would just up and fail for no good reason). I've migrated it over to a 3GHz Pentium D/1GB box with great results. It could use a bit more RAM as I still see swap being used, but it's not spending its entire time operating out of swap and can stay up for more than 48 hours.

If you're curious how loaded the CPU and RAM are, install htop ("apt-get install htop" for those running Debian or Ubuntu) and give it a run. All the utility of top, plus some nice graphs showing CPU, RAM, and swap load. Watch it for a few hours of operation and you can easily see where any slowdowns are coming from.

[jholder]

Great tips.

Just an FYI, 64 bit requires more mem than 32 bit because memory management changes. The instructions are larger, thus the memory requirements are larger.

1 GB on 32 bit is not that same as 1 gb on 64 bit
Maoni's WebLog : 64-bit vs 32-bit