Setting the property to 64k made the throughput jump to 36mb/sec, 39mb for 128k.
Thank you for the tip. From: Michael Katzenellenbogen [mailto:mich...@cloudera.com] Sent: Thursday, January 03, 2013 7:28 PM To: user@hadoop.apache.org Subject: Re: Hadoop throughput question What is the value of the io.file.buffer.size property? Try tuning it up to 64k or 128k and see if this improves performance when reading SequenceFiles. -Michael On Jan 3, 2013, at 7:00 PM, Artem Ervits <are9...@nyp.org<mailto:are9...@nyp.org>> wrote: I will follow up on that certainly, thank you for the information. So further investigation showed that counting SequenceFile records takes about 26mb/sec. If I simply read bytes on the same cluster and the same file, the speed is 70mb/sec. Is there a configuration for optimizing SequenceFile processing? Thank you. From: John Lilley [mailto:john.lil...@redpoint.net] Sent: Thursday, January 03, 2013 6:09 PM To: user@hadoop.apache.org<mailto:user@hadoop.apache.org> Subject: RE: Hadoop throughput question Unless the Hadoop processing and the OneFS storage are co-located, MapReduce can't schedule tasks so as to take advantage of data locality. You would basically be doing a distributed computation against a separate NAS, so throughput would be limited by the performance properties of the Insilon NAS and the network switch architecture. Still, 26MB/sec in aggregate is far worse than what I'd expect Insilon to deliver, even over a single 1GB connection. john From: Artem Ervits [mailto:are9...@nyp.org]<mailto:[mailto:are9...@nyp.org]> Sent: Thursday, January 03, 2013 4:02 PM To: user@hadoop.apache.org<mailto:user@hadoop.apache.org> Subject: RE: Hadoop throughput question Hadoop is using OneFS, not HDFS in our configuration. Isilon NAS and the Hadoop nodes are in the same datacenter but as far as rack locations, I cannot tell. From: John Lilley [mailto:john.lil...@redpoint.net] Sent: Thursday, January 03, 2013 5:15 PM To: user@hadoop.apache.org<mailto:user@hadoop.apache.org> Subject: RE: Hadoop throughput question Let's suppose you are doing a read-intensive job like, for example, counting records. This is will be disk bandwidth limited. On a 4-node cluster with 2 local SATA on each node you should easily read 400MB/sec in aggregate. When you are running the Hadoop cluster, is the Hadoop processing co-located with the Ilsilon nodes? Is Hadoop configured to use OneFS or HDFS? John From: Artem Ervits [mailto:are9...@nyp.org]<mailto:[mailto:are9...@nyp.org]> Sent: Thursday, January 03, 2013 3:00 PM To: user@hadoop.apache.org<mailto:user@hadoop.apache.org> Subject: Hadoop throughput question Hello all, I'd like to pick the community brain on average throughput speeds for a moderately specced 4-node Hadoop cluster with 1GigE networking. Is it reasonable to expect constant average speeds of 150-200mb/sec on such setup? Forgive me if the question is loaded but we're Hadoop cluster with HDFS served via EMC Isilon storage. We're getting about 30mb/sec with our machines and we do not see a difference in job speed between 2 node cluster and 4 node cluster. Thank you. -------------------- This electronic message is intended to be for the use only of the named recipient, and may contain information that is confidential or privileged. 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