On Fri, Aug 5, 2011 at 10:21 AM, M. C. Srivas <mcsri...@gmail.com> wrote:
> On Fri, Aug 5, 2011 at 9:42 AM, Jean-Daniel Cryans <jdcry...@apache.org>wrote:
>
>> On Fri, Aug 5, 2011 at 8:52 AM, M. C. Srivas <mcsri...@gmail.com> wrote:
>> > The normal behavior would be for the HMaster to make the hlog read-only
>> > before processing it.... very simple fencing and works on all Posix or
>> > close-to-Posix systems. Does that not work on HDFS?
>>
>> I'm sure you know the answer to that :)
>>
>
> Actually, I really don't know HDFS details ... so does chmod work for all?
>
> We're thinking for submitting a patch to Hbase that does the following:
>
> recoverLease() {
> if (fs is DistributedFileSystem) {
> call the NN's recover lease API
> } else if (fs supports setPermissions) {
> call fs.setPermissions
In most filesystems, permissions are only checked when a file is
opened, not on every write. That's true of HDFS as well as Linux's
behavior with all local filesystems I'm aware of. As far as I know
it's the case with most NFS filers as well. Hence the existence of
explicit fencing commands accessible via remote administrative
interfaces on NetApps, for example.
-Todd
--
Todd Lipcon
Software Engineer, Cloudera
