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Yuki Morishita edited comment on CASSANDRA-7386 at 7/25/14 6:59 PM: -------------------------------------------------------------------- [~lyubent] I have [branch|https://github.com/yukim/cassandra/tree/7386] that writes WriteValues to csv for analysis. Feel free to use it. was (Author: yukim): [~lyubent] I have [branch](https://github.com/yukim/cassandra/tree/7386) that writes WriteValues to csv for analysis. Feel free to use it. > JBOD threshold to prevent unbalanced disk utilization > ----------------------------------------------------- > > Key: CASSANDRA-7386 > URL: https://issues.apache.org/jira/browse/CASSANDRA-7386 > Project: Cassandra > Issue Type: Improvement > Components: Core > Reporter: Chris Lohfink > Assignee: Lyuben Todorov > Priority: Minor > Fix For: 2.1.1 > > Attachments: 7386-v1.patch, 7386v2.diff, Mappe1.ods, > patch_2_1_branch_proto.diff > > > Currently the pick the disks are picked first by number of current tasks, > then by free space. This helps with performance but can lead to large > differences in utilization in some (unlikely but possible) scenarios. Ive > seen 55% to 10% and heard reports of 90% to 10% on IRC. With both LCS and > STCS (although my suspicion is that STCS makes it worse since harder to be > balanced). > I purpose the algorithm change a little to have some maximum range of > utilization where it will pick by free space over load (acknowledging it can > be slower). So if a disk A is 30% full and disk B is 5% full it will never > pick A over B until it balances out. -- This message was sent by Atlassian JIRA (v6.2#6252)