NFS Share for HDFS Storage support multiple mount points ?

[#1]

Customer is asking us to build a cluster with VMs based on NFS Share for HDFS Storage. Can NFS Share support multiple mount points ?

[#2 · Accepted solution]

@hrongali@hortonworks.com

VMs based on NFS - Not a good idea (Performance impact) There is best practice document from VMware on this that you may want to look at.

Can NFS Share support multiple mount points ?

Yes if you meant if we can mount NFS share to multiple hosts.

[#3]

Also, robustness of NFS implementation varies a lot by vendor, and consequently the level of parallelism allowed. A low-end NAS box will only be able to handle a few simultaneous accesses. Something higher-end, like a big NetApp box, can probably handle a lot more, although with performance impact as Neeraj said. Also, don't forget to look at the effective network bandwidth between individual VMs and the NFS server, and the total bandwidth utilizable by the NFS server. VMs often have severely restricted bandwidth allocations configured, and both VMs and the NFS server will be limited by the mathematical constraints of sharing physical resources.

[#4]

@mfoley@hortonworks.com Good point! Thank you for sharing.

[#5]

Makes sense, Thanks for sharing

[#6]

Just curious - why do they want to do this? The HDFS reliability model assumes we are writing replicas to independent physical disks. Also connectivity issues between the DataNodes and the NFS server will likely show up as strange new failure modes.

Matt and Neeraj already mentioned performance concerns.

[#7]

Customer doesnt have space for physical servers. They want to set up an environment based on VMs with Isilion(Non-HDFS) storage as local. We have communicated the performance caveats and they understand. This is to demonstrate ONLY functionality from POC perspective. They will be moving to Isilon HDFS Storage soon once they have the necessary patches in place for HDP 2.3