Moving on from 2008 Xserve for school network

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Moving on from 2008 Xserve for school network

I manage a small school network of about 125 MacBooks (white 2007/2009), and 40 iMacs (mostly 2008/2009) which are bound to a 2008 Xserve running 10.6.8. The laptops and desktops are also all on 10.6.8. It's been quite stable, but we're now running into software compatibility issues because of Snow Leopard's age.

More importantly we might be getting a bunch of new MacBooks for next year, and I need to help figuring out how to integrate them into the network. Since new machines will have Yosemite, I'll probably have to upgrade to OS X Server to Yosemite which isn't supported on 2008 Xserves.

How do I go forward? My predecessor, who created the network, suggested I get a linux box to host the network home and group folders, and use a Mac Mini to manage the logins. Does that sound like a reasonable plan?

We also have 30 iPads bound to a laptop running Configurator. Might be nice to use a new Mac server to manage those and anything more we might get.

A bit more info...

The Xserve isn't doing too much; all it does is authenticate network logins, and manage network home and group folders. It's also our DNS and DHCP server, and I also use NetBoot for re-imaging clients and for filtering out student mobile devices from accessing the network. It doesn't serve email, iCal, printers or apps. I use workgroup manager to create accounts and manage group access to shared folders. It also serves a few internal web pages.

Most of the client configuration (including setting ip printers) is done with login scripts using iHook.

I also have an identical xserve from when we had two campuses. All it does is run a proxy server to limit web access to whitelist for our younger students. And it also serves our library catalog software.

The iMacs and most of the laptops have maxed out RAM and can run Mavericks/Yosemite. I might even swap out the HDs with SSDs to get more life out of the old laptops.

Xserve, OS X Server, Xserve 2,1 running 10.6.8

Posted on Apr 22, 2015 1:34 AM

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Answer 1

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cdhw

Level 4

3,588 points

Apr 22, 2015 3:32 AM in response to gsa-tech

You'd have to know enough about Kerberos to to get the Linux box to accept credentials from the Mini. I've never got beyond the 'life is too short for this...' barrier on that one. (There is another recent thread 'Kerberos request for help' in this forum asking for help on this very topic.)

My solution to essentially the same problem you have has been to replace each Xserve with a 2.8 GHz Intel Core i5 Mac Mini with 16 GB ram and a 1TB fusion drive, add a thunderbolt to ethernet adaptor to get 2Gb/s (bonded) ethernet, and a Promise Pegassus2 R4 disk array to store the user accounts. I'd have preferred 4-core Minis, but the last one was sold about a week before I bought. :-(

The Pegassus 2 I'm using has 4 x 2TB drives which I've configured as 1 x 2TB for Time Machine Backups, 2 x 2TB a RAID-1 pair for user home directories with the fourth 2 TB disk on standby as a 'global revert spare'. If the Promise 2 detects issues with one of the other disks it will use the spare to take over and send me an email. It plugs into the Thunderbolt interface on the Mini. Things like netboot images, Deploy Studio Server, etc. live on the internal (fusion) drive of the Mini.

As far as I can tell the bottleneck on this system is the 2Gb bonded ethernet (i.e. 250 MB/s). The Promise 2 RAID-1 appears to be able to saturate this both reading and writing. (You can use RAID 0 or RAID 5 for even better performance if you have the budget.)

I currently have two of these systems. If one Mini packs up I should be able to just daisy chain both the Pegassus 2 drives off the remaining Mini while I nip down the Apple Centre to buy another one.

I don't claim my solution is optimal, but it's cheap and simple and I'm happy with it at the moment.

C.

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Answer 2

gsa-tech Author

Level 1

4 points

Apr 24, 2015 3:35 PM in response to cdhw

Thanks cdhw. How many clients are running on this system? If I have 100 - 150 simultaneous clients, will the extra cpu power of a mac pro be of any performance benefit?

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Answer 3

cdhw

Level 4

3,588 points

Apr 30, 2015 12:49 AM in response to gsa-tech

If you have seen it already, you'll want to read the Xserve Transitioning Guide:

http://images.apple.com/xserve/pdf/L422277A_Xserve_Guide.pdf

It very much depends on how users are using the clients: browsing the web puts very different demands on the system to visualising MRI datasets. I'm working on a rule of thumb of about 40 simultaneous network home directory logins per Mini+Pegasus; I suspect that they can handle twice that.

I've not yet had a chance to stress test the system (most students are away revising for exams and there are no classes running) but I'm not worried; if I need another couple of Minis when things get busy I'll buy them. I didn't get Mac Pros because they were three or four times the price of a Mini and I'd have had to get at least two of them to provide redundancy.

To a large extent it depends on one's attitude to risk. I'm happy to spend when I know it is necessary but I hate paying Mac Pro prices for kit that ends up sitting idle.

C.

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Answer 4

gsa-tech Author

Level 1

4 points

Apr 30, 2015 1:01 AM in response to cdhw

Awesome, thanks. My hope is that with new laptops, students will be able to use iMovie, write code, and do some 3D design instead of always having to the lab.

While it'd be overkill, I'm going to ask for a couple of refurbished new Mac Pros so I can run Mavericks on them. I can always use the extra horsepower to transcode video files.

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Answer 5

cdhw

Level 4

3,588 points

Apr 30, 2015 9:27 AM in response to gsa-tech

"My hope is that with new laptops, students will be able to use iMovie, write code, and do some 3D design instead of always having to the lab."

These are just the sort of activities that stress network home directories. For these you want to use 'portable/mobile home directories' (or whatever they are called these days) and train the students to use the same client each time.

However fast your server is, you will always be limited to a few hundred MB/s SHARED by the ethernet connections.

C.

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Answer 6

gsa-tech Author

Level 1

4 points

Apr 30, 2015 9:38 AM in response to cdhw

So far iMovie '09 has worked well with network homes using Snow Leopard on our 2009 era iMacs. We give accounts permission to use iMovie Events.localized on the root of the hard drive so all the media is local and fast. So they do know they have to use the same computer in those cases. I'm open to moving mobile homes if the demand arises, but it's more of a pain when they want to use the iMacs in the lab for more screen real estate, mice, etc. That, and I've been reading that mobile homes on Yosemite clients haven't been playing nice with Mavericks servers.

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