Editing Storage (section)

=== Server Side Caching ===
Although not strictly a standalone storage technology, server side caching can be used to both massively boost  performance in your homelab, and make sure that any existing investments you have in (for example) your whitebox or vendor NAS / array is maximised, and you get the most longevity out of your existing kit.

Server side caches typically come in two flavours, read only and read/write, the former of which is becoming more and more rare.

Some example server side caching vendors are:
* [[PernixData]]
* [[Intel Cache Acceleration Software]]
* [[VMware vSphere Flash Read Cache (vFRC)]]

The biggest benefits with server side caching in the homelab are
* You simply provision a single SSD in each physical compute host in your lab, and you will immediately get some significant performance benefits. No need to do all-flash at your shared storage (or even use up expensive NAS slots with SSDs), just fill that full of a few spindles for plenty of capacity.
* Due to the fact that you are unlikely to be running all of your homelab VMs are full utilisation all of the time, the VM storage working set it likely to revolve mostly around whatever you are testing at the time, so you don't have to have massive SSDs to achieve generally decent performance.
* You can retro-fit server-side caching to an existing lab very easily with the addition of an SSD to each host, and a bit of software!

Disadvantages include:
* Missed read cache hits. 90% or more of your IOs may hit the server side cache and have sub millisecond latencies, but anything which doesn't will be performance limited by the maximum latency of your spindle-based storage. In the real world this can be a significant issue for business critical applications, but in the homelab this is not such a big deal! The same applies to any form of cachine or even scale-out distributed multi-tier storage as well, if your working set exceeds your flash size.
* You typically require a minimum of 2-3 compute nodes to support server side caching, each of which will require an SSD, so this is not a low-budget option.