While upgrading my home lab recently I found myself reconsidering the scale up vs scale out argument. There are countless articles about building your own home lab and whitebox hardware but is there a good alternative to the accepted ‘two whiteboxes and a NAS’ scenario that’s so common for entry level labs? I’m studying for the VCAP5-DCD so while the ‘up vs out’ discussion is a well trodden path there’s value (for me at least) in covering it again.
There are two main issues with many lab (and production) environments, mine included;
- Memory is a bottleneck and doubly so in labs using low end hardware – the vCentre appliance defaults to 8GB, as does vShield Manager so anyone wanting to play with vCloud (for example) needs a lot of RAM.
- Affordable yet performant shared storage is also a challenge – I’ve used both consumer NAS (from 2 to 5 bays) and ZFS based appliances but I’m still searching for more performance.
In an enterprise environment there are a variety of solutions to these challenges – memory density is increasing (up to 512GB per blade in the latest UCS servers for example) and on the storage front SSDs and flash memory have spurred innovations in the storage battle. In particular Fusion-IO have had great success with their flash memory devices which reduce the burden on shared storage while dramatically increasing performance. I was after something similar but without the budget.
When I built my newest home lab server, the vHydra I used a dual socket motherboard to maximise the possible RAM (up to 256GB RAM) and used local SSDs to supplement my shared storage. This has allowed me to solve the two issues above – I have a single server which can host a larger number of VMs with minimal reliance on my shared storage. The concepts are the same as solutions like Fusion-IO aim to do in production environments but mine isn’t particularly scalable. In fact it doesn’t really scale at all – I’ll have to revert to centralised storage if I buy more servers. Nor does it have any resilience – the ESXi server itself isn’t clustered and the storage is a single point of failure as there’s no RAID. It is cheap however, and for lab testing I can live with those compromises. None of this is vaguely new of course – Simon Gallagher’s vTardis has been using these same concepts to provide excellent lab solutions for years. Is this really a poor man’s Fusion-IO? There’s nothing like the peformance and nothing like the budget but the objectives are the same but to be honest it’s probably a slightly trolling blog title. I won’t do it again. Promise!
If you’re thinking of building a home lab from scratch consider buying a single large server with local SSD storage instead of multiple smaller servers with shared storage. You can always scale out later or wait for Ceph or HDFS to elimate the need for centralised storage at all…
Tip: It’s worth bearing in mind the 32GB limit on the free version of ESXi – unless you’re a vExpert or they reinstate the VMTN subscription you’ll be stuck with 60 day eval editions if you go above 32GB (or buying a licence!).