You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@pegasus.apache.org by GitBox <gi...@apache.org> on 2021/03/15 03:09:21 UTC
[GitHub] [incubator-pegasus] Shuo-Jia commented on a change in pull request #695: doc: add disk-migrater rfc
Shuo-Jia commented on a change in pull request #695:
URL: https://github.com/apache/incubator-pegasus/pull/695#discussion_r594022492
##########
File path: rfcs/2021-02-22-disk-migrater.md
##########
@@ -0,0 +1,66 @@
+# Disk-Migrater
+
+## Design Goals
+Disk-Migrater is for migrating data among different local disks within one node. This feature is different from node-rebalance that is for migrating data among different nodes.
+
+## Flow Process
+Disk-Migrater operates by sending `RPC_REPLICA_DISK_MIGRATE` rpc to the targeted node that triggers the node to migrate the specified replica from one disk to another. The whole migration process is as follow:
+
+```
++---------------+ +---------------+ +--------------+
+| Client(shell) +------+ replicaServer +-------+ metaServer |
++------+--------+ +-------+-------+ +-------+------+
+ | | |
+ +------migrateRPC-----> +-----IDLE |
+ | | | (validate rpc)|
+ | | MOVING |
+ | | | (migrate data)|
+ | | MOVED |
+ | | | (rename dir) |
+ | | CLOSED |
+ | | | |
+ | +----- +<----LEARN<------------+
+ | | | |
+ | | | |
+ | LearnSuccess| |
+ | | | |
+ | | | |
+ | +----->+ |
+```
+
+1. The targeted node receives the migrateRPC and starts validating the request arguments.
+2. If the RPC is valid, node starts migrating the specified replica.
+3. After replica migration finishes successfuly, the original replica will be closed and ReplicaServer re-opens the new replica.
+4. If the new replica's data is inconsistent with its primary, MetaServer will automatically start to trigger replica-learn to catch up with the latest data.
+5. After the learning process is completed, the entire disk-migration ends.
+
+## Replica States
+In the process of migration, the original replica and the new replica will have different states as follow:
+| process |origin replica status[dir name] | new replica status[dir name] |
+|---|---|---|
+|IDEL |primary/secondary[gpid.pegasus] |--[--] |
+|START |secondary[gpid.pegasus] |--[--] |
+|MOVING |secondary[gpid.pegasus] |--[gpid.pegasus.disk.migrate.tmp] |
+|MOVED |secondary[gpid.pegasus] |--[gpid.pegasus.disk.migrate.tmp] |
+|CLOSED |error[gpid.pegasus.disk.migrate.ori] |--[gpid.pegasus] |
+|LEARNING |error[gpid.pegasus.disk.migrate.ori] |potential_secondary[gpid.pegasus] |
+| COMPLETED |error[gpid.pegasus.disk.migrate.ori] |secondary[gpid.pegasus] |
Review comment:
?, how format? now has been md fomat
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@pegasus.apache.org
For additional commands, e-mail: dev-help@pegasus.apache.org