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https://issues.apache.org/jira/browse/AMQ-6441?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15532687#comment-15532687
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Tim Bain commented on AMQ-6441:
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This approach addresses the immediate problem, with an 8 EB volume. It will do
nothing for a 16EB volume, a 32 EB volume, or any other multiple of 16 EB,
because those volumes will all show as small positively-sized volumes. (If 8EB
is 4193 bytes over half the range of a long, double that - 16 EB - will be 4193
* 2 = 8386 bytes over the full range of a long, and will mod down to the small
but positive remainder: 8386 bytes. And multiplying that number by anything
will result in a volume that is 8386 bytes times the multiplier, which will
probably be smaller than the KahaDB store.) So the proposed (and implemented)
algorithm fixes today's problem, but does nothing for the next problem.
The only safe way to allow people to not be bit by this in the future is to
implement the flag. It would be defaulted to false, and enabled only when they
deem it necessary based on their own knowledge of their storage situation.
People don't go changing values randomly, so no one's going to make the change
unless they believe they need it, and if they know about the setting to
misconfigure it, they'll know what to set back when it causes them problems.
Based on the above, I recommend rejecting the pull request that was just made,
and reworking the change to include a flag. Otherwise, we're going to get to
do this all over again whenever Amazon increases the default EFS volume size to
16EB.
> Incorrect File System Size Reported with Amazon Elastic File System (EFS)
> -------------------------------------------------------------------------
>
> Key: AMQ-6441
> URL: https://issues.apache.org/jira/browse/AMQ-6441
> Project: ActiveMQ
> Issue Type: Bug
> Affects Versions: 5.11.1
> Reporter: Ismail Bhana
>
> I've set up Active MQ in production with a shared file system master/slave
> configuration (KahaDB). I've set everything up and mounted the EFS on both
> EC2 instances.
> When I check the disk free stats I get 8 exabytes for the shared file system:
> {code}
> $ df -h
> eu-west-1a.***.efs.eu-west-1.amazonaws.com:/ 8.0E 0 8.0E 0% /mnt/efs
> {code}
> Unfortunately, ActiveMQ cannot interpret this number (8 exabytes). This may
> be due to integer truncation.
> Here is a snippet of the log:
> {code}
> Store limit is 102400 mb (current store usage is 0 mb). The data directory:
> /mnt/efs/kahadb only has -8796093022208 mb of usable space - resetting to
> maximum available disk space: -8796093022207 mb
> Store limit is -8796093022207 mb, whilst the max journal file size for the
> store is: 32 mb, the store will not accept any data when used.
> {code}
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