>>I'm especially concerned about long pauses causing zk session timeouts and >>consequent RS shutdowns. Our boxes do have a lot of RAM and we are >>exploring how we can use more of it for the cluster while maintaining >>overall stability.
Suraj, what is the maximum GC pause you have observed in your cluster so far? I do not think s-t-w GC pause on 8GB heap will lasts longer than 5-8 secs. Best regards, Vladimir Rodionov Principal Platform Engineer Carrier IQ, www.carrieriq.com e-mail: [email protected] ________________________________________ From: Suraj Varma [[email protected]] Sent: Monday, July 08, 2013 11:09 AM To: [email protected] Subject: GC recommendations for large Region Server heaps Hello: We have an HBase cluster with region servers running on 8GB heap size with a 0.6 block cache (it is a read heavy cluster, with bursty write traffic via MR jobs). (version: hbase-0.94.6.1) During HBaseCon, while speaking to a few attendees, I heard some folks were running region servers as high as 24GB and some others in the 16GB range. So - question: Are there any special GC recommendations (tuning parameters, flags, etc) that folks who run at these large heaps can recommend while moving up from an 8GB heap? i.e. for 16GB and for 24GB RS heaps ... ? I'm especially concerned about long pauses causing zk session timeouts and consequent RS shutdowns. Our boxes do have a lot of RAM and we are exploring how we can use more of it for the cluster while maintaining overall stability. Also - if there are clusters running multiple region servers per host, I'd be very interested to know what RS heap sizes those are being run at ... and whether this was chosen as an alternative to running a single RS with large heap. (I know I'll have to test the GC stuff out on my cluster and for my workloads anyway ... but just trying to get a feel of what sort of tuning options had to be used to have a stable HBase cluster with 16 or 24GB RS heaps). Thanks in advance, --Suraj Confidentiality Notice: The information contained in this message, including any attachments hereto, may be confidential and is intended to be read only by the individual or entity to whom this message is addressed. If the reader of this message is not the intended recipient or an agent or designee of the intended recipient, please note that any review, use, disclosure or distribution of this message or its attachments, in any form, is strictly prohibited. If you have received this message in error, please immediately notify the sender and/or [email protected] and delete or destroy any copy of this message and its attachments.
