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https://issues.apache.org/jira/browse/HDFS-7877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15861802#comment-15861802
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Manoj Govindassamy commented on HDFS-7877:
------------------------------------------
[~mingma],
[~dilaver] brought up a good point regarding the restrictions put for the range
allowed for the configuration {{dfs.namenode.maintenance.replication.min}}.
Currently the allowed range for Maintenance Min Replication is {{0 to
dfs.namenode.replication.min(default=1)}}. Users wanting not to affect the
performance of the cluster would wish to have the Maintenance Min Replication
number greater than 1, say 2. In the current design, it is possible to have
this Maintenance Min Replication configuration, but only after changing the
NameNode level Block Min Replication to 2, and which could slowdown the overall
latency for client writes.
Technically speaking we should be allowing Maintenance Min Replication to be in
range {{0 to dfs.replication.max}}. There is always config value of 0 for users
not wanting any availability/performance during maintenance. And, performance
centric workloads can still get maintenance done without major disruptions by
having a bigger Maintenance Min Replication. So, any reasons why you wanted to
have Maintenance Min Replication range to be restrictive and less than or equal
to {{dfs.namenode.replication.min}} ? May be i am overlooking something here.
Please clarify.
{noformat}
if (minMaintenanceR < 0) {
throw new IOException("Unexpected configuration parameters: "
+ DFSConfigKeys.DFS_NAMENODE_MAINTENANCE_REPLICATION_MIN_KEY
+ " = " + minMaintenanceR + " < 0");
}
if (minMaintenanceR > minR) {
throw new IOException("Unexpected configuration parameters: "
+ DFSConfigKeys.DFS_NAMENODE_MAINTENANCE_REPLICATION_MIN_KEY
+ " = " + minMaintenanceR + " > "
+ DFSConfigKeys.DFS_NAMENODE_REPLICATION_MIN_KEY
+ " = " + minR);
{noformat}
> Support maintenance state for datanodes
> ---------------------------------------
>
> Key: HDFS-7877
> URL: https://issues.apache.org/jira/browse/HDFS-7877
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: datanode, namenode
> Reporter: Ming Ma
> Assignee: Ming Ma
> Attachments: HDFS-7877-2.patch, HDFS-7877.patch,
> Supportmaintenancestatefordatanodes-2.pdf,
> Supportmaintenancestatefordatanodes.pdf
>
>
> This requirement came up during the design for HDFS-7541. Given this feature
> is mostly independent of upgrade domain feature, it is better to track it
> under a separate jira. The design and draft patch will be available soon.
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