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 >