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
Why Nutanix is not like Stonefly or your typical VSAN appliance
Thanks for taking a look at Nutanix Complete Cluster, Chris, and hope we get a chance to show you the product in action soon. Maybe at vmworld?
We believe the comparison with Stonefly is not completely accurate, so wanted to share some more detail.
Stonefly seems to simply consume a server's worth of local PCIe SSD and then serve it up via an iSCSI target. In contrast, Nutanix provides a fully redundant , scale-out, clustered solution. That means that storage from PCIe SSD and accompanying SATA drives from all nodes across the cluster are aggregated and presented as a single name space & iSCSI target – what we call Scale-Out Converged Storage (SOCS). High performance comes from the VM data being constantly optimized to be local and simultaneously replicated and distributed across all nodes in the cluster for redundancy.
The Nutanix architecture leverages distributed systems techniques pioneered by Google (we have key architects, eg our CTO, who worked on GFS and Oracle Exadata), and can thus scale to hundreds of nodes seamlessly in a building-block architecture. Growing storage and compute resources is as simple as adding another node. With Stonefly, it seems that only one server is providing the data, and if that server dies, then down goes the entire population of VMs. Perhaps they can provide an active-active solution, two nodes, but they'd be limited in the long term in terms of scalability.
Feature-wise, we're providing enterprise-class functionality like HA, DR, thin provisioning, HOT (heat-optimized tiering), VM-based policies, backup and more to be announced soon, so to be clear, this is not meant to be an SMB solution, but rather a simpler, more scalable, and dramatically lower cost alternative to vBlocks/FlexPods, for enterprise virtualization use cases.
BTW, we are aiming to be 100% channel driven, so interested resellers should contact us here: http://www.nutanix.com/partners.html.
- The Nutanix Product Team