A first glance into Nutanix storage
Once over lightly
What can we expect from the Nutanix Complete Cluster in a storage sense? Here's an instant review of what the documentation tells us.
The Nutanix product does exactly what HP's P400 VSA does, only more so and in a full-bodied way. It virtualises direct-attached storage ( DAS) across servers to function as a storage area network for VMs in those servers. It uses dedicated flash for metadata and active data, disk drives for less active data, and 10gigE as a cluster interconnect.
The trend of bring storage and compute resources closer together was pioneered, among others, by Sun, with its Honeycomb NAS product. The trend of virtualising DAS into a SAN was pioneered by iSCSI SAN pioneer LeftHand Networks and its Virtual Storage Appliance (VSA), not to be confused with VMware's VSA.
Nutanix is not alone by the way, in creating a virtual SAN out of server flash and DAS disks. StoneFly has a virtual SAN appliance that uses Fusion-io PCIe flash drives plus the host server's hard disk drives.
It is ironic that Nutanix is using EMC-owned software – VMware – to build compute-plus-storage blocks aimed to replace EMC VMAX and VNX SAN storage arrays. Interestingly EMC could do a reverse-Nutanix by running app VMs on spare VMAX engines... in theory.
Three storage tiers
Nutanix says it has three kinds of storage media per node: 320GB Fusion-io PCIe flash, 300GB Intel SATA interface solid state drives (SSD), and five 1TB, 7,200rpm Seagate disk drives.
Why does it have two kinds of flash media? A Nutanix spokesperson said: "The 300GB Intel SSD is the boot SSD for each host. It also serves as swap space in case of high density VDI workloads. The PCIe SSD is the main workhorse of the system - the HOT (Heat Optimized tiering) Cache, Flash Store, metadata sits on the PCIe SSD."
Checking Fusion-io product specs, there are two products that could be used: a 320GB 2-bit muti-level cell (MLC) ioDrive, or a 320GB faster single-level cell (SLC) ioDrive Duo. It's actually the MLC ioDrive
Checking Intel's SSD products there appear to be two choices as well: the 320 – a 300GB 2-bit MLC desktop/notebook SSD – or the 710, again a 2-bit MLC product but using better-class NAND. Both have a 3Gbit/s SATA interface. Nutanix says the Intel 320 SSD is used
We're told the disk drives are 1TB, 7,200rpm SATA drives from Seagate. This is a 1TB Constellation drive according to Nutanix, a 4-platter drive as we understand it.
Next page: Flash cache use