Unsolved
This post is more than 5 years old
25 Posts
0
800
Isilon Netezza Interoperability
IBM and EMC have a common customer that is having trouble configuring NFS Client Access from an IBM server to an EMC/Isilon array. Specifically, file writes to exported folders set up for streaming is very slow. They have already tried following Isilon best practices for NFS client setup and there has been no improvement in performance. The write performance issue appears to be peculiar to the IBM Netezza Appliance - Isilon combination as the IBM appliance is able to write to other network storage without issue and the Isilon array is providing better performance on writes to other client machines.
Are there any best practices document for Isilon and IBM netezza?
Peter_Sero
1.2K Posts
1
September 12th, 2013 02:00
If you are using multiple connections to the Isilon,
are the connections evenly distributed across the nodes?
(SmartConnect can't help much if one client starts
numerous connections based on a single DNS query.
If there is one query per connection,
but all within a few seconds, round-robin
need to be used in SmartConnect rather than
load-based policies.)
Next, how exactly are the writes accomplished from the Netazza
(as compared to the better performing clients)?
Use isi statistics client (--long)
and identify the operations from the client
in question (RemoteName/RemoteAddr).
Check:
- In (and Out): throughput per "connection" (multiple connections between
the same IPs (LocalName--RemoteName) a coalesced into a single line though).
- Class: read vs write vs namespace operations: streaming write loads
should mostly show large 'write' ops and few if any non-write ops.
- Ops: oprate/sec, very high (with small request size, InAvg)? very low (with large TimeAvg)?
- TimeAvg: time spent within the Isilon per request (in usec):
10000usec=10msec would be considered high.
- (with --long:) InAvg (and OutAvg): average request sizes, e.g. 4K would be too small for streaming...
In case you see mainly large writes (as considered good), compute
TimeAvg-in-seconds times Ops-per-second:
- TimeAvg/1000000 x Ops = Utilization rate per "connection"
if substantially below 1, then latencies outside the Isilon occur, like
network latencies or client-side delays/queuing problems.
(Edit 9/13: Utilization rate: here not the storage utilization w.r.t. protection
overhead, but utilization of a processing unit, Little's law - Wikipedia, the free encyclopedia)
Short story: The Netazza should show a pattern clearly different
from the ok clients. Once identified, appropriate
means can be investigated.
-- Peter