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https://issues.apache.org/jira/browse/HBASE-13996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14701605#comment-14701605
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Andrew Purtell commented on HBASE-13996:
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No problem at all [~liushaohui].
This is fine for when the canary is using the default canary table name
"hbase:canary". It's the explanation to the user that Stack asked for.
{code}
+ } else if (tableName.equals(Canary.CANARY_TABLE_NAME)){
+ description = "The hbase:canary table is used to sniff the write
availbility of each regionserver.";
{code}
However, I think the tool should allow for the user to give a different name
for the canary table. The default can be "hbase:canary" of course and nobody
would need to change it today. However I can see a future time when we could
have different resource allocation and admission control policies by namespace
and in that case a user might want to run a separate canary instance for the
different namespaces that are in use.
Since we are publishing write timing, should the size of the value being
written be configurable? This way a user can also watch for latency blips when
processing their use case's average or p95 or whatever value size. Should be
fine, we will hold down the total amount of data written because each iteration
of the canary will rewrite the same locations. Minor detail, feel free to
ignore.
Should this interval be configurable?
{code}
+ // check canary distribution for every 10 minutes
{code}
Should the slop factor be configurable?
{code}
+ if (numberOfRegions < numberOfServers * regionsPerServer * 0.7
+ || numberOfRegions > numberOfServers * regionsPerServer * 1.5) {
{code}
Why 30% less but 50% more?
Ah, even better, we are setting TTLs on the canary family data. Great. Should
this be adjustable? Perhaps with a command line option.
{code}
+ family.setTimeToLive(24 * 60 * 60 * 1000);
{code}
Should be good feedback for now (smile)
> Add write sniffing in canary
> ----------------------------
>
> Key: HBASE-13996
> URL: https://issues.apache.org/jira/browse/HBASE-13996
> Project: HBase
> Issue Type: Improvement
> Components: canary
> Affects Versions: 0.98.13, 1.1.0.1
> Reporter: Liu Shaohui
> Assignee: Liu Shaohui
> Fix For: 2.0.0, 1.3.0, 0.98.15
>
> Attachments: HBASE-13996-v001.diff, HBASE-13996-v002.diff
>
>
> Currently the canary tool only sniff the read operations, it's hard to
> finding the problem in write path.
> To support the write sniffing, we create a system table named '_canary_' in
> the canary tool. And the tool will make sure that the region number is large
> than the number of the regionserver and the regions will be distributed onto
> all regionservers.
> Periodically, the tool will put data to these regions to calculate the write
> availability of HBase and send alerts if needed.
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