[Gluster-devel] Improving Geo-replication Status and Checkpoints
Aravinda
avishwan at redhat.com
Tue Feb 3 17:30:56 UTC 2015
Today we discussed about Geo-rep Status design, summary of the discussion.
- No usecase for "Deletes pending" column, should we retain it?
- No separate column for Active/Passive. Worker can be Active/Passive
only when worker is Stable(It can't be Faulty and Active)
- Rename "Not Started" status as "Created"
- Checkpoint columns will be retained in the Status output till we
support Multiple checkpoints. Three columns instead of Single
column(Completed, Checkpoint time and Completion time)
- Still we have confusion about "Files Pending" and "Files Synced", What
numbers it has to show. Georep can't map the number to exact count on disk.
Venky suggested to show Entry, Data and Metadata pending as three
columns. (Remove "Files Pending" and "Files Synced")
- Rename "Files Skipped" to "Failures"
Status output proposed:
-----------------------
MASTER NODE - Master node hostname/IP
MASTER VOL - Master volume name
MASTER BRICK - Master brick path
SLAVE USER - Slave user to which geo-rep is established.
SLAVE - Slave host and Volume name(HOST::VOL format)
STATUS - Created/Initializing../Started/Active/Passive/Stopped/Faulty
LAST SYNCED - Last synced time(Based on stime xattr)
CRAWL STATUS - Hybrid/History/Changelog
CHECKPOINT STATUS - Yes/No/ N/A
CHECKPOINT TIME - Checkpoint Set Time
CHECKPOINT COMPLETED - Checkpoint Completion Time
Not yet decided
---------------
FILES SYNCD - Number of Files Synced
FILES PENDING - Number of Files Pending
DELETES PENDING- Number of Deletes Pending
FILES SKIPPED - Number of Files skipped
ENTRIES - Create/Delete/MKDIR/RENAME etc
DATA - Data operations
METADATA - SETATTR, SETXATTR etc
Let me know your suggestions.
--
regards
Aravinda
On 02/02/2015 04:51 PM, Aravinda wrote:
> Thanks Sahina, replied inline.
>
> --
> regards
> Aravinda
>
> On 02/02/2015 12:55 PM, Sahina Bose wrote:
>>
>> On 01/28/2015 04:07 PM, Aravinda wrote:
>>> Background
>>> ----------
>>> We have `status` and `status detail` commands for GlusterFS
>>> geo-replication, This mail is to fix the existing issues in these
>>> command outputs. Let us know if we need any other columns which
>>> helps users to get meaningful status.
>>>
>>> Existing output
>>> ---------------
>>> Status command output
>>> MASTER NODE - Master node hostname/IP
>>> MASTER VOL - Master volume name
>>> MASTER BRICK - Master brick path
>>> SLAVE - Slave host and Volume name(HOST::VOL format)
>>> STATUS - Stable/Faulty/Active/Passive/Stopped/Not Started
>>> CHECKPOINT STATUS - Details about Checkpoint completion
>>> CRAWL STATUS - Hybrid/History/Changelog
>>>
>>> Status detail -
>>> MASTER NODE - Master node hostname/IP
>>> MASTER VOL - Master volume name
>>> MASTER BRICK - Master brick path
>>> SLAVE - Slave host and Volume name(HOST::VOL format)
>>> STATUS - Stable/Faulty/Active/Passive/Stopped/Not Started
>>> CHECKPOINT STATUS - Details about Checkpoint completion
>>> CRAWL STATUS - Hybrid/History/Changelog
>>> FILES SYNCD - Number of Files Synced
>>> FILES PENDING - Number of Files Pending
>>> BYTES PENDING - Bytes pending
>>> DELETES PENDING - Number of Deletes Pending
>>> FILES SKIPPED - Number of Files skipped
>>>
>>>
>>> Issues with existing status and status detail:
>>> ----------------------------------------------
>>>
>>> 1. Active/Passive and Stable/faulty status is mixed up - Same column
>>> is used to show both active/passive status as well as Stable/faulty
>>> status. If Active node goes faulty then by looking at the status it
>>> is difficult to understand Active node is faulty or the passive one.
>>> 2. Info about last synced time, unless we set checkpoint it is
>>> difficult to understand till what time data is synced to slave. For
>>> example, if a admin want's to know all the files synced which are
>>> created 15 mins ago, it is not possible without setting checkpoint.
>>> 3. Wrong values in metrics.
>>> 4. When multiple bricks present in same node. Status shows Faulty
>>> when one of the worker is faulty in that node.
>>>
>>> Changes:
>>> --------
>>> 1. Active nodes will be prefixed with * to identify it is a active
>>> node.(In xml output active tag will be introduced with values 0 or 1)
>>> 2. New column will show the last synced time, which minimizes the
>>> use of checkpoint feature. Checkpoint status will be shown only in
>>> status detail.
>>> 3. Checkpoint Status is removed, Separate Checkpoint command will be
>>> added to gluster cli(We can introduce multiple Checkpoint feature
>>> with this change)
>>> 4. Status values will be "Not
>>> Started/Initializing/Started/Faulty/Stopped". Stable is changed to
>>> "Started"
>>> 5. Slave User column will be introduced to show to which user
>>> geo-rep session is established.(Useful in Non root geo-rep)
>>> 6. Bytes pending column will be removed. It is not possible to
>>> identify the delta without simulating sync. For example, we are
>>> using rsync to sync data from master to slave, If we need to know
>>> how much data to be transferred then we have to run the rsync
>>> command with --dry-run flag before running actual command. With
>>> tar-ssh we have to stat all the files which are identified to be
>>> synced to calculate the total bytes to be synced. Both are costly
>>> operations which degrades the geo-rep performance.(In Future we can
>>> include these columns)
>>> 7. Files pending, Synced, deletes pending are only session
>>> information of the worker, these numbers will not match with the
>>> number of files present in Filesystem. If worker restarts, counter
>>> will reset to zero. When worker restarts, it logs previous session
>>> stats before resetting it.
>>> 8. Files Skipped is persistent status across sessions, Shows exact
>>> count of number of files skipped(Can get list of GFIDs skipped from
>>> log file)
>>> 9. "Deletes Pending" column can be removed?
>>
>> Is there any way to know if there are errors syncing any of the
>> files? Which column would that reflect in?
> "Skipped" Column shows number of files failed to sync to Slave.
>
>> Is the last synced time - the least of the synced time across the nodes?
> Status output will have one entry for each brick, so we are planning
> to display last synced time from that brick.
>>
>>
>>>
>>> Example output
>>>
>>> MASTER NODE MASTER VOL MASTER BRICK SLAVE USER
>>> SLAVE STATUS LAST SYNCED CRAWL
>>> ----------------------------------------------------------------------------------------------------------------
>>>
>>> * fedoravm1 gvm /gfs/b1 root fedoravm3::gvs
>>> Started 2014-05-10 03:07 pm Changelog
>>> fedoravm2 gvm /gfs/b2 root fedoravm4::gvs
>>> Started 2014-05-10 03:07 pm Changelog
>>>
>>> New Status columns
>>>
>>> ACTIVE_PASSIVE - * if Active else none.
>>> MASTER NODE - Master node hostname/IP
>>> MASTER VOL - Master volume name
>>> MASTER BRICK - Master brick path
>>> SLAVE USER - Slave user to which geo-rep is established.
>>> SLAVE - Slave host and Volume name(HOST::VOL format)
>>> STATUS - Stable/Faulty/Active/Passive/Stopped/Not Started
>>> LAST SYNCED - Last synced time(Based on stime xattr)
>>> CHECKPOINT STATUS - Details about Checkpoint completion
>>> CRAWL STATUS - Hybrid/History/Changelog
>>> FILES SYNCD - Number of Files Synced
>>> FILES PENDING - Number of Files Pending
>>> DELETES PENDING- Number of Deletes Pending
>>> FILES SKIPPED - Number of Files skipped
>>>
>>>
>>> XML output
>>> active
>>> master_node
>>> master_node_uuid
>>> master_brick
>>> slave_user
>>> slave
>>> status
>>> last_synced
>>> crawl_status
>>> files_syncd
>>> files_pending
>>> deletes_pending
>>> files_skipped
>>>
>>>
>>> Checkpoints
>>> ===========
>>> New set of Gluster CLI commands will be introduced for Checkpoints.
>>>
>>> gluster volume geo-replication <VOLNAME> <SLAVEHOST>::<SLAVEVOL>
>>> checkpoint create <NAME> <DATE>
>>> gluster volume geo-replication <VOLNAME> <SLAVEHOST>::<SLAVEVOL>
>>> checkpoint delete <NAME>
>>> gluster volume geo-replication <VOLNAME> <SLAVEHOST>::<SLAVEVOL>
>>> checkpoint delete all
>>> gluster volume geo-replication <VOLNAME> <SLAVEHOST>::<SLAVEVOL>
>>> checkpoint status [<NAME>]
>>> gluster volume geo-replication <VOLNAME> checkpoint status # For
>>> all geo-rep sessions for that volume
>>> gluster volume geo-replication checkpoint status # For all
>>> geo-rep sessions for all volumes
>>>
>>>
>>> Checkpoint Status:
>>>
>>> SESSION NAME Completed Checkpoint
>>> Time Completion Time
>>> -----------------------------------------------------------------------------------------
>>>
>>> gvm->root at fedoravm3::gvs Chk1 Yes 2014-11-30 11:30 pm
>>> 2014-12-01 02:30 pm
>>> gvm->root at fedoravm3::gvs Chk2 No 2014-12-01 10:00 pm N/A
>>
>> Can the time information have the timezone information as well? Or is
>> this UTC time?
>> (Same comment for last synced time)
> Sure. Will have UTC time in Status output.
>>
>>>
>>> XML output:
>>> session
>>> master_uuid
>>> name
>>> completed
>>> checkpoint_time
>>> completion_time
>>>
>>>
>>> --
>>> regards
>>> Aravinda
>>> _______________________________________________
>>> Gluster-devel mailing list
>>> Gluster-devel at gluster.org
>>> http://www.gluster.org/mailman/listinfo/gluster-devel
>>
>
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