good suggestion.
On Wed, Apr 17, 2013 at 4:10 PM, Harsh J <ha...@cloudera.com> wrote:
> Pardon my late inquisition here but since HBase already shipped out
> with a name .snapshots/, why do we force them to change it, and not
> rename HDFS' snapshots to use .hdfs-snapshots, given that HDFS
> Snapshots has not been released for any users yet. The way I see it,
> that'd be much more easier to do than making a workaround for a done
> deal on HBase, which already has its snapshot's users.
>
> @Tsz-Wo - If the snapshots in HDFS aren't a 'generic' feature
> applicable to other FileSystem interface implementations as well, then
> .hdfs-snapshots should be fine for it - no?
>
> On Wed, Apr 17, 2013 at 2:32 AM, Ted Yu <yuzhih...@gmail.com> wrote:
> > Hi,
> > Please take a look at patch v5 attached to HBASE-8352.
> >
> > It would be nice to resolve this blocker today so that 0.94.7 RC can be
> cut.
> >
> > Thanks
> >
> > On Tue, Apr 16, 2013 at 10:12 AM, lars hofhansl <la...@apache.org>
> wrote:
> >
> >> Please see my last comment on the jira. We can make this work without
> >> breaking users who are using HDFS snapshots.
> >>
> >> ------------------------------
> >> *From:* Ted Yu <yuzhih...@gmail.com>
> >> *To:* d...@hbase.apache.org
> >> *Cc:* hdfs-dev@hadoop.apache.org; lars hofhansl <la...@apache.org>
> >> *Sent:* Tuesday, April 16, 2013 10:00 AM
> >> *Subject:* Re: collision in the naming of '.snapshot' directory between
> >> hdfs snapshot and hbase snapshot
> >>
> >> Let's get proper release notes for HBASE-8352 .
> >>
> >> Either Lars or I can send out notification to user mailing list so that
> >> there is enough preparation for this change.
> >>
> >> Cheers
> >>
> >> On Tue, Apr 16, 2013 at 8:46 AM, Jonathan Hsieh <j...@cloudera.com>
> wrote:
> >>
> >> I was away from keyboard when I asserted that hdfs snapshot was a hadoop
> >> 2.1 or 3.0 feature. Apparently it is targeted as a hadoop 2.0.5
> feature.
> >> (I'm a little surprised -- expected this to be a hadoop2 compat
> breaking
> >> feature) -- so I agree that this is a bit more urgent.
> >>
> >> Anyway, I agree that the fs .snapshot naming convention is long standing
> >> and should win.
> >>
> >> My concern is with breaking compatibility in 0.94 again -- if we don't
> go
> >> down the conf variable route, I consider having docs to properly
> document
> >> how to do the upgrade and caveats of doing the upgrade in the
> docs/release
> >> notes blocker to hbase 0.94.7. (specifically mentioning from 0.94.6 to
> >> 0.94.7, and to possibly to 0.95).
> >>
> >> Jon.
> >>
> >> On Mon, Apr 15, 2013 at 9:00 PM, Ted Yu <yuzhih...@gmail.com> wrote:
> >>
> >> > bq. Alternatively, we can detect the underlying Hadoop version, and
> use
> >> > either .snapshot or .hbase_snapshot in 0.94 depending on h1 & h2.
> >> >
> >> > I think this would introduce more confusion, especially for
> operations.
> >> >
> >> > Cheers
> >> >
> >> > On Mon, Apr 15, 2013 at 8:52 PM, Enis Söztutar <enis....@gmail.com>
> >> wrote:
> >> >
> >> > > Because HDFS exposes the snapshots so that the normal file system
> >> > > operations are mapped inside snapshot dirs, I think HDFS reserving
> the
> >> > > .snapshot name makes sense. OTOH, nothing is specific about the dir
> >> name
> >> > > that is chosen by HBase.
> >> > >
> >> > > I would prefer to change the dir name in 0.94 as well, since 0.94 is
> >> also
> >> > > being run on top of hadoop 2. Alternatively, we can detect the
> >> underlying
> >> > > Hadoop version, and use either .snapshot or .hbase_snapshot in 0.94
> >> > > depending on h1 & h2.
> >> > >
> >> > > Enis
> >> > >
> >> > >
> >> > > On Mon, Apr 15, 2013 at 8:31 PM, Ted Yu <yuzhih...@gmail.com>
> wrote:
> >> > >
> >> > > > bq. let's make the hbase snapshot for a conf variable.
> >> > > >
> >> > > > Once we decide on the new name of snapshot directory, we should
> still
> >> > use
> >> > > > hardcoded value. This aligns with current code base:
> >> > > > See this snippet from HConstants:
> >> > > >
> >> > > > public static final List<String> HBASE_NON_TABLE_DIRS =
> >> > > >
> >> > > > Collections.unmodifiableList(Arrays.asList(new String[] {
> >> > > > HREGION_LOGDIR_NAME,
> >> > > >
> >> > > > HREGION_OLDLOGDIR_NAME, CORRUPT_DIR_NAME, SPLIT_LOGDIR_NAME,
> >> > > >
> >> > > > HBCK_SIDELINEDIR_NAME, HFILE_ARCHIVE_DIRECTORY,
> >> > SNAPSHOT_DIR_NAME,
> >> > > > HBASE_TEMP_DIRECTORY }));
> >> > > > Cheers
> >> > > >
> >> > > > On Mon, Apr 15, 2013 at 8:24 PM, Jonathan Hsieh <j...@cloudera.com
> >
> >> > > wrote:
> >> > > >
> >> > > > > constraints:
> >> > > > >
> >> > > > > 1) hbase 0.94.6 is released and .snapshot is hardcoded in there.
> >> > > > > 2) hdfs snapshots is a Hadoop 2.1 or 3.0 feature. I doubt that
> it
> >> > will
> >> > > > ever
> >> > > > > make it to 1.x. This hdfs feature ideally this shouldn't affect
> >> > > current
> >> > > > A
> >> > > > > pache Hbase 0.94.x's.
> >> > > > > 3) hbase 95/96 may default to Hadoop1 or Hadoop 2. these
> versions
> >> > > should
> >> > > > > pick a different table snapshot name to respect fs conventions.
> >> > > > >
> >> > > > > proposed actions:
> >> > > > >
> >> > > > > 1) let's make the hbase snapshot for a conf variable. (hbase.
> >> > > > > snapshots.dir) let's change the default for hbase 95+. (maybe
> >> > > > > .hbase-snapshots). we'll also port this patch to 0.94.x
> >> > > > > 2) let's publish instructions on how to update the hbase
> snapshot
> >> > dir:
> >> > > > > shutdown hbase, config update, rename dir, restart hbase.
> >> > > > > 3) I lean towards leaving the current default hbase snapshot
> dir in
> >> > 94
> >> > > > > since it shouldn't be affected. upgrading hbase to 95/96 will
> >> > require
> >> > > > > shutdown and update scripts so it seems like the ideal time to
> >> > > autoforce
> >> > > > > this default change.
> >> > > > >
> >> > > > > Thoughts?
> >> > > > >
> >> > > > >
> >> > > > > On Monday, April 15, 2013, lars hofhansl wrote:
> >> > > > >
> >> > > > > > OK. Let's try to fix that quickly, so that I can release HBase
> >> > > 0.94.7.
> >> > > > > >
> >> > > > > > -- Lars
> >> > > > > >
> >> > > > > >
> >> > > > > >
> >> > > > > > ________________________________
> >> > > > > > From: Ted Yu <yuzhih...@gmail.com>
> >> > > > > > To: d...@hbase.apache.org; hdfs-dev@hadoop.apache.org
> >> > > > > > Sent: Monday, April 15, 2013 7:13 PM
> >> > > > > > Subject: collision in the naming of '.snapshot' directory
> between
> >> > > hdfs
> >> > > > > > snapshot and hbase snapshot
> >> > > > > >
> >> > > > > >
> >> > > > > > Hi,
> >> > > > > > This afternoon Huned ad I discovered an issue while playing
> with
> >> > > HBase
> >> > > > > > Snapshots on top of Hadoop's Snapshot branch (
> >> > > > > >
> http://svn.apache.org/viewvc/hadoop/common/branches/HDFS-2802/).
> >> > > > > >
> >> > > > > > HDFS (built from HDFS-2802 branch) doesn't allow paths with
> >> > .snapshot
> >> > > > as
> >> > > > > a
> >> > > > > > component while HBase tries to create paths with .snapshot as
> a
> >> > > > > component.
> >> > > > > > This leads to issues in HBase, and one of HDFS or HBase needs
> to
> >> > give
> >> > > > up
> >> > > > > > the .snapshot reserved keyword. HBase released Snapshots
> feature
> >> in
> >> > > > > 0.94.6
> >> > > > > > (quite recently) and it may not be too late to change HBase to
> >> use
> >> > a
> >> > > > > > different path component in an upcoming new release.
> >> > > > > >
> >> > > > > > In HBase these path names are not user visible. If there is a
> >> > > > deployment
> >> > > > > of
> >> > > > > > 0.94.6, one could provide a migration tool that renames
> .snapshot
> >> > to
> >> > > > > > .hbase-snapshot or something to be able to move to the
> Snapshot
> >> > > release
> >> > > > > of
> >> > > > > > Hadoop. On the other hand, .snapshot in HDFS is a user visible
> >> name
> >> > > and
> >> > > > > is
> >> > > > > > a convention that is used by many file systems. It's a matter
> of
> >> > > > > > familiarity with such path names that would help users in
> using
> >> > HDFS
> >> > > > > > snapshots.
> >> > > > > >
> >> > > > > > I am including the hdfs-dev in this email. Would appreciate
> if we
> >> > > could
> >> > > > > > work together and come up with a solution.
> >> > > > > >
> >> > > > > > You can find sample output from hdfs command here:
> >> > > > > > http://pastebin.com/bBqR4Fvr
> >> > > > > >
> >> > > > > > Cheers
> >> > > > >
> >> > > > >
> >> > > > >
> >> > > > > --
> >> > > > > // Jonathan Hsieh (shay)
> >> > > > > // Software Engineer, Cloudera
> >> > > > > // j...@cloudera.com
> >> > > > >
> >> > > >
> >> > >
> >> >
> >>
> >>
> >>
> >> --
> >> // Jonathan Hsieh (shay)
> >> // Software Engineer, Cloudera
> >> // j...@cloudera.com
> >>
> >>
> >>
> >>
> >>
>
>
>
> --
> Harsh J
>
