Scale Computing had added flash storage capability to its 2150 and 4150 hyper-converged hardware. It has also added flash tiering and, with a nod to legendary rock-umentary Spinal Tap, has built in the ability to “turn it up to 11” and pin specified workloads to the solid state storage tier.
Previously only offering spinning disk HDD capacity, Scale now allows the deployment of an extra drive, with one SAS-connected flash disk per node.
This is added as a tier of storage rather than as cache. A user-configurable slider goes from 0 to 11 and allows the customer to set a virtual disk’s relationship to the flash cache, with 0 pinning a virtual disk to spinning disk, 1-10 representing an increasing priority to use of the flash tier and 11 pinning a virtual disk to flash.
From settings 1 to 10 a heat map algorithm identifies the hottest blocks from virtual disks (there can be up to 12 per virtual machine) in the node that should go to flash.
With another nod to Spinal Tap, Scale Computing has opted to delve into the “where are they now file” and uses SLC flash in 400GB and 800GB capacities as the flash option.
SLC (single level cell) flash was the main type of enterprise flash in the early days. It allows just one 1/0 switch per cell (hence the name) compared to the two found in MLC (multi-level cell) but offered better I/O performance.
But SLC has fallen from favour. It’s cost has increased and its storage density decreased compared to MLC and eMLC implementations. Now it’s very rare to find a storage array maker that offers SLC.
But eMLC and MLC are likely to be offered in the not too distant future, said Scale’s co-founder and chief evangelist, Jason Collier.
He said, “SLC is definitely the more costly option but we looked at MLC and eMLC and we wanted something with more sustainable life and went with the tried-and-tested SLC. Having said that, we are going to move to MLC and eMLC options in future.”