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https://issues.apache.org/jira/browse/HBASE-7912?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14612142#comment-14612142
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Vladimir Rodionov commented on HBASE-7912:
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[~mbertozzi] wrote:
{quote}
you should probably wait or coordinate with the guys over HBASE-13991
{quote}
I joined the watch list, thanks
Now your questions:
{quote}
assuming that on the WAL there are multiple regions, is there any logic to
decide that using hfiles instead of wal is better? or do you want always the
full ability to restore up to "a specific seqid"?
{quote}
First of all, we do not restore to a specific seqId, we restore a specific
backup image, which in turn, for each table is a combination of a last snapshot
and sequence of WAL files. WAL conversion to HFiles is a way to improve restore
performance, because HFiles we just copy over to restore location and WAL files
we have to replay.
{quote}
when do you decide to "compact the wals" on the backup? who is doing that the
backup manger?
{quote}
Its a manual procedure which can be executed by system (global) admin. When to
run it is up to this person to decide.
{quote}
when you export to another media, who is responsible to compact the wals?
{quote}
Exporting to another media is the artifact from the original design, feature
which won't be supported. I will update the doc. If by compacting wals you mean
- converting them to HFiles or merging backup images, then this is manual
procedures (you will have to run hbase backup convert/merge tool).
{quote}
in the document there is mention of "convert the wals to hfiles", in this way
we loose the ability to restore up to "a specific seqid", which goes back to
the question, if we don't need that, is there any logic to decide that using
hfiles instead of wal is better for incremental?
{quote}
Thanks for this question, it turned out that original design has a flaw we have
not noticed before. As since we do not record last backed up seqId and do not
restore up to that seqId - that is kind of tricky imo, there will be some
duplicates of KVs in store files after incremental restore. These duplicates
are result of how we do full backup and first incremental backup after full.
During full backup we perform distributed log roll and record, for every RS,
last WAL timestamp, then we do snapshot. The next WAL after recorded will make
it into next incremental backup set, but it will contains some edits (puts,
deletes) which have been recorded by a previous snapshot. During restore, we
first restore snapshot, then we will replay WALs and create some duplicates of
KVs in different store files.
> HBase Backup/Restore Based on HBase Snapshot
> --------------------------------------------
>
> Key: HBASE-7912
> URL: https://issues.apache.org/jira/browse/HBASE-7912
> Project: HBase
> Issue Type: Sub-task
> Reporter: Richard Ding
> Assignee: Vladimir Rodionov
> Labels: backup
> Fix For: 2.0.0
>
> Attachments: HBaseBackupRestore-Jira-7912-DesignDoc-v1.pdf,
> HBaseBackupRestore-Jira-7912-DesignDoc-v2.pdf,
> HBaseBackupRestore-Jira-7912-v4.pdf, HBase_BackupRestore-Jira-7912-CLI-v1.pdf
>
>
> Finally, we completed the implementation of our backup/restore solution, and
> would like to share with community through this jira.
> We are leveraging existing hbase snapshot feature, and provide a general
> solution to common users. Our full backup is using snapshot to capture
> metadata locally and using exportsnapshot to move data to another cluster;
> the incremental backup is using offline-WALplayer to backup HLogs; we also
> leverage global distribution rolllog and flush to improve performance; other
> added-on values such as convert, merge, progress report, and CLI commands. So
> that a common user can backup hbase data without in-depth knowledge of hbase.
> Our solution also contains some usability features for enterprise users.
> The detail design document and CLI command will be attached in this jira. We
> plan to use 10~12 subtasks to share each of the following features, and
> document the detail implement in the subtasks:
> * *Full Backup* : provide local and remote back/restore for a list of tables
> * *offline-WALPlayer* to convert HLog to HFiles offline (for incremental
> backup)
> * *distributed* Logroll and distributed flush
> * Backup *Manifest* and history
> * *Incremental* backup: to build on top of full backup as daily/weekly backup
> * *Convert* incremental backup WAL files into hfiles
> * *Merge* several backup images into one(like merge weekly into monthly)
> * *add and remove* table to and from Backup image
> * *Cancel* a backup process
> * backup progress *status*
> * full backup based on *existing snapshot*
> *-------------------------------------------------------------------------------------------------------------*
> *Below is the original description, to keep here as the history for the
> design and discussion back in 2013*
> There have been attempts in the past to come up with a viable HBase
> backup/restore solution (e.g., HBASE-4618). Recently, there are many
> advancements and new features in HBase, for example, FileLink, Snapshot, and
> Distributed Barrier Procedure. This is a proposal for a backup/restore
> solution that utilizes these new features to achieve better performance and
> consistency.
>
> A common practice of backup and restore in database is to first take full
> baseline backup, and then periodically take incremental backup that capture
> the changes since the full baseline backup. HBase cluster can store massive
> amount data. Combination of full backups with incremental backups has
> tremendous benefit for HBase as well. The following is a typical scenario
> for full and incremental backup.
> # The user takes a full backup of a table or a set of tables in HBase.
> # The user schedules periodical incremental backups to capture the changes
> from the full backup, or from last incremental backup.
> # The user needs to restore table data to a past point of time.
> # The full backup is restored to the table(s) or to different table name(s).
> Then the incremental backups that are up to the desired point in time are
> applied on top of the full backup.
> We would support the following key features and capabilities.
> * Full backup uses HBase snapshot to capture HFiles.
> * Use HBase WALs to capture incremental changes, but we use bulk load of
> HFiles for fast incremental restore.
> * Support single table or a set of tables, and column family level backup and
> restore.
> * Restore to different table names.
> * Support adding additional tables or CF to backup set without interruption
> of incremental backup schedule.
> * Support rollup/combining of incremental backups into longer period and
> bigger incremental backups.
> * Unified command line interface for all the above.
> The solution will support HBase backup to FileSystem, either on the same
> cluster or across clusters. It has the flexibility to support backup to
> other devices and servers in the future.
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