Quick Lab Infrastructure Win

Hopefully the first of at least a few blogs which gives some details on what I’m going to call ‘The Quick Wins’.


How to quickly deploy updated/custom Virtual Machine images in N523?


N523 was previously a classroom, not a computer lab, so it wasn’t originally cabled with enough network ports for 24 PCs.
It certainly wasn’t cabled with enough ports or even electricity to be what is now our Cybersecurity Lab.
IT and estates converted the room into the 24 PC lab you now see, but with a couple of limitations; 100Mb Ethernet to the PC’s and a single 1Gb Fibre Uplink to the wider campus.
For day-day surfing, email or lab tasks this copes reasonably well but when a new VM image is required on each of the 24 PCs, it’s a problem!

A single Windows VM image could be 40GB, Linux images are around 10GB (we currently have at least 4 Windows and 3 Linux VMs on each PC in N523).


100Mb, so slow!

A 100Mb ethernet link will move data at around 11MB/s, so a single 40GB VM image can take around an hour to copy to a lab PC.

The 1Gb uplink can perhaps cope with 9 or 10 simultaneous 100Mb transfers from the campus network into N523.
Assuming no other traffic, no labs in progress, and whatever server in the campus is sufficiently quiet to allow us to pull a full 1Gb of traffic from it.
Updating 24 PCs takes? Best case 3 hours? Just for one VM image!

Our IT team have provided great support in scheduling work to deploy VMs into the labs, but they can only manage it when nothing else is happening and plenty of warning for it to finish copying. Time for the fix.


We’ve been fortunate over the last 12months or so to have some equipment donated from local companies, now we can put it to use.

Within the lab we can install a local 1Gb switch, giving approx 100MB/s to each PC, but we’re still limited by the uplink speed to the rest of the campus.
In theory, our 3 hours would be reduced to 2 and a half hours. Not a great improvement.

Amongst the equipment donated, we’ve been given some simple 1-U rack mount servers. Nothing fancy, but they do have RAID and 3 x 1Gb network cards.
By hanging one of these on the back of the equipment racks as a NAS (Network Attached Storage) we can store our VM images locally within the lab, then distribute them within the room.
NIC Teaming (bonding) allows all three 1Gb network cards to balance the network traffic amongst them. Giving approx 300MB/s from the host.
Mirroring the RAID (RAID1), gives redundancy (failure is ALWAYS an option), but also allows multiple disks to serve files simultaneously.
Which depending on the models of disk, should be around 200 – 300MB/s.


100% Disk and 99% Network Utilisation!



Zoom Zoom!

It seems like a lot of effort to reduce our 3 hours to; maybe if we’re lucky, 1 hour.​
But the hidden advantage is if we need to update or fix just a few or even a single machine.
Copying one VM image to just a single PC would have previously taken an hour. Now we can do that in less than 7 minutes!

Worth remembering, 24 x 40,000MB is 960GB (a Terabyte near enough), even with todays technology it’s a LOT of data to move around.