Progress indicator for Xtrabackup SST

[Raghavendra D Prabhu]

Should be easy to add with du and pv on the joiner side. (for
both rsync and xtrabackup SSTs)

[Raghavendra D Prabhu (raghavendra-prabhu)]

However, note that, when using compression, it won't be accurate. For an accurate progress, xtrabackup has to implement it.

[Alex Yurchenko (ayurchen)]

IMO there are several more principal issues:
1 - initially joiner may not know the total amount of data to be transferred (at least with rsync)
2 - when clobbering files in-place the percentage may be simply jumping back and forth around 90% or so (at least with rsync).
3 - with xtrabackup joiner needs to undergo prepare stage which also needs to be reflected somehow in the overall progress, with rsync it actually does a similar thing on startup.
4 - in general the joiner cannot be accessed by mysql client, so the only place it can report the progress is error log.

On donor this must be easier, but it can only reflect donor progress.

[Raghavendra D Prabhu (raghavendra-prabhu)]

a) Yes, this is only for donor progress (ie. progress of data
transfer with xtrabackup or rsync). The total amount is roughly
calculated based on ibd/ibdata1/MYD/MYI sizes (from du).

b) The clobbering shouldn't matter since we are only measuring on
donor.

c) Regarding the prepare stage, xtrabackup itself prints some
progress to the error log (like 10 20 30 ... 100). However, there
may be a few stages after transfer but before prepare like
decompression which won't be counted here.

d) For #4, yes, the error log is only place for joiner.

Since a major chunk of SST time is spent with transfer it is better to
print this (also this progress is what affects both donor and joiner,
whereas after transfer, only joiner is affected).The prepare stage of
xtrabackup is currently serial (though it may be parallelized in future
by xtrabackup), hence can be slow as well (for very big databases), but
even then the transfer duration will be higher.

[Jay Janssen (jay-janssen)]

On Jun 23, 2013, at 3:32 AM, Raghavendra D Prabhu <email address hidden> wrote:

> a) Yes, this is only for donor progress (ie. progress of data
> transfer with xtrabackup or rsync). The total amount is roughly
> calculated based on ibd/ibdata1/MYD/MYI sizes (from du).

I presume then that this would only appear on the Donor side (in the Donor's logs somewhere). Make sure it's clearly labeled something like:

"Donor data transfer progress"

and not

"SST progress"

Since there obviously may be other steps on the joiner unaccounted for.

Jay Janssen, MySQL Consulting Lead, Percona
http://about.me/jay.janssen

[Raghavendra D Prabhu (raghavendra-prabhu)]

Seems like MEB added progress indicator in 3.8.2:

https://blogs.oracle.com/mysqlenterprisebackup/entry/mysql_enterprise_backup_3_81
https://dev.mysql.com/doc/mysql-enterprise-backup/3.8/en/backup-progress-report-options.html

[Raghavendra D Prabhu (raghavendra-prabhu)]

Based on #5, I will raise a similar request for PXB.

[Raghavendra D Prabhu (raghavendra-prabhu)]

Regarding progress, it can also be added on joiner if the size is communicated to joiner beforehand.

[Raghavendra D Prabhu (raghavendra-prabhu)]

There is also a lp:1079336 for progress, however, that deals with only a certain component of backup and not the entire streaming procedure.

[Raghavendra D Prabhu (raghavendra-prabhu)]

Note, this progress indication is being added for xtrabackup SST for now. For other SST methods - rsync (for whom should be simpler with --progress initially) and mysqldump, it will be added separately.

[Raghavendra D Prabhu (raghavendra-prabhu)]

Created lp:1197014 for that.

[Alex Yurchenko (ayurchen)]

fixed by porting Percona changes

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXC-1072