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https://issues.apache.org/jira/browse/BOOKKEEPER-199?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13416086#comment-13416086
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Sijie Guo commented on BOOKKEEPER-199:
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@Rakesh,
{quote}
1. Utility functions for checking disk problem
{quote}
Is the utility a separated tool that admin guys could run to check disk? Which
scenarios it would be used?
{quote}
4. Provide mechanism to detect r-o bookie by the bookie clients
{quote}
as Flavio's suggestion,
{quote}
One option I see is to have the bookie removing itself from the list of
available bookies in zookeeper so that the administrator is able to determine
that the bookie has declared itself faulty. The administrator can be notified
of the change through a zookeeper watcher. In the meanwhile, the bookie is able
to respond to read requests for which it has data. How does it sound?
{quote}
if bookie server encountered IOException and not able to write to disks, it
removed itself from available bookies list and doesn't shutdown. so the bookie
server could still severing read requests. there is only one minor drawback for
this solution is that there is no place to track all the r-o bookies list. so
we need a separated znode to hold all r-o bookies for tracking.
so turning a bookie to r-o mode would be remove itself from available bookies
list and put itself in r-o bookies list.
so if did it in this way, I think there is no changes in bookie client. we just
need to change bookie server to do action when encountering too many
IOExceptions:
1) remove bookie znode but doesn't shutdown (turning to r-o)
2) shutdown the bookie server
1) and 2) could be set as a configuration setting to let user decide what to
do, which I called it as strategy as previous comment.
{code}
5. Provide admin command to start the bookie in read-only mode
{code}
agreed to provide the command to start bookie in read-only mode. I think for
read-only mode, we just starts the bookie server which it would add itself into
r-o bookies list.
How is your opinion?
> Provide bookie readonly mode, when journal/ledgers flushing has failed with
> IOE
> -------------------------------------------------------------------------------
>
> Key: BOOKKEEPER-199
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-199
> Project: Bookkeeper
> Issue Type: Bug
> Components: bookkeeper-server
> Affects Versions: 4.0.0
> Reporter: Rakesh R
> Assignee: Rakesh R
> Priority: Critical
> Fix For: 4.2.0
>
> Attachments: BOOKKEEPER-199.patch
>
>
> Bookkeeper should change to readonly(r-o) mode when the journal/ledgers
> flushing has failed with IOException. Later on, reject write requests on
> server side and will accept only the read requests from the clients, because
> even if flushing fails, the data in the bookie which has been flushed is
> still valid.
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