+1. Large number of regions (> 1000) per RS + heavy load - this is what we have in our environment (staging and productions)
Its not 0.92, of course. Its 90.4 (we just upgraded staging to 90.5) Some observations: 1. Holes in .META. which can be resolved by cluster restart (but we had one incident recently, when restart did not help and OfflineMetaRepair utility did not help, we lost ALL data in a staging grid.) Most of the time it manifests itself with NotServingRegion exceptions. 2. Real loss of data (small fraction of). We observe this regularly when we restart cluster some tables report different (lesser) row counts. We almost gave up on that and decided totally rewrite our data load path using bulk loader. I think our operations engineers would add more bullets to this list. Probably, these issues have been resolved (to some extent) in 0.92 but we are not ready to jump on Titanic yet :) We will wait until it safely crosses the Atlantic. Best regards, Vladimir Rodionov Principal Platform Engineer Carrier IQ, www.carrieriq.com e-mail: [email protected] ________________________________________ From: Jonathan Hsieh [[email protected]] Sent: Friday, January 06, 2012 9:43 AM To: [email protected] Subject: Stress testing releases candidates Hey all, I'm curious about the kinds of testing you all do and which paths you exercise before +1'ing a release candidate (or putting it into production). Do you just simulate the expected workloads you have at your installations? How much testing do you all do on error recovery paths or when HBase gets into a stressful place? Jimmy and I've been doing long-running TestLoadAndVerify from Bigtop using different configurations including a stressful (flush/split/compact heavy, properties below) configuration with the recent 0.92 release candidates. TestLoadAndVerify basically are two sequentially executed MR jobs -- one that loads data that have "dependency chains" on previous writes, and one that verifies that all chains are satisfied (link below). At the moment we've been manually injecting faults (killing meta, masters, root, random rs's, pausing them to simulate GC's) but will be likely injecting faults and exercising recovery paths more regularly and systematically. This approach has resulted in some of the recent dist log splitting deadlocks Jimmy's been working. I've encountered a few "transient" data missing problems that I'm still trying to duplicate and isolate. Best I can say now is that it seems to happen if/when region servers have a large number of regions (roughly 900-2000 regions per range). More specifically, in these particular cases it seems that the verify job return a list of sequential rows indicating that a region is was temporarily unavailable or not returning data. Interestingly, when I run just the verify job again later on the same table, all rows are present. Since the Load and Verify jobs are two consecutively run MR jobs, my guess is that there is a related in something time delayed (balancing, splitting, compaction?). Thanks, Jon. Here's how to setup bigtop: https://cwiki.apache.org/confluence/display/BIGTOP/Setting+up+Bigtop+to+run+HBase+system+tests Here's the patch I've been using. https://issues.apache.org/jira/browse/BIGTOP-321 Here's part of the stress configuration that stresses flushing, splitting, and balancing operations. ---- <!-- stress settings --> <property> <name>io.file.buffer.size</name> <value>131072</value> <description>Hadoop setting </description> </property> <property> <name>hbase.hregion.max.filesize</name> <value>4194304</value> <!-- 4MB --> <!-- <value>268435456</value> 256MB, for lots of flushes without splits --> <description> Maximum HStoreFile size. If any one of a column families' HStoreFiles has grown to exceed this value, the hosting HRegion is split in two. Default: 256M. </description> </property> <property> <name>hbase.balancer.period </name> <value>2000</value> <description>Period at which the region balancer runs in the Master. </description> </property> <property> <name>hbase.hregion.max.filesize</name> <value>4194304</value> <!-- 4MB --> <!-- <value>268435456</value> 256MB, for lots of flushes without splits --> <description> Maximum HStoreFile size. If any one of a column families' HStoreFiles has grown to exceed this value, the hosting HRegion is split in two. Default: 256M. </description> </property> <property> <name>hbase.balancer.period </name> <value>2000</value> <description>Period at which the region balancer runs in the Master. </description> </property> <property> <name>hbase.hregion.memstore.flush.size</name> <value>262144</value> <!-- 256KB --> <description> Memstore will be flushed to disk if size of the memstore exceeds this number of bytes. Value is checked by a thread that runs every hbase.server.thread.wakefrequency. (normally 64 MB) </description> </property> ---- -- // Jonathan Hsieh (shay) // Software Engineer, Cloudera // [email protected] 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. 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