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Bug #9256

zfs send space estimation off by > 10% on some datasets

Added by Brad Lewis about 2 years ago. Updated about 2 years ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Category:
-
Start date:
2018-03-09
Due date:
% Done:

100%

Estimated time:
Difficulty:
Medium
Tags:
needs-triage
Gerrit CR:

Description

Here is an instance where we see a big discrepancy.

$ zfs send c -e -vvvv domain0/group-117/oracle_db_container-118/oracle_timeflow-119/datafile@oracle_snapshot-73 > /tmp/foo
full send of domain0/group-117/oracle_db_container-118/oracle_timeflow-119/datafile@oracle_snapshot-73 estimated size is 411M
total estimated size is 411M
TIME SENT BLOCKS SNAPSHOT
22:24:36 355M 171838 domain0/group-117/oracle_db_container-118/oracle_timeflow-119/datafile@oracle_snapshot-73
$ ls -lh /tmp/foo
-rw-r--r- 1 delphix staff 470M Jun 22 22:24 /tmp/foo
$

estimate is : 431217656 bytes
actual size is : 492215048 bytes

Without the -e flag, the discrepancy is much higher.

$ zfs send c -vvvv domain0/group-117/oracle_db_container-118/oracle_timeflow-119/datafile@oracle_snapshot-73 > /tmp/foo
full send of domain0/group-117/oracle_db_container-118/oracle_timeflow-119/datafile@oracle_snapshot-73 estimated size is 411M
total estimated size is 411M
TIME SENT BLOCKS SNAPSHOT
22:25:47 428M 115392 domain0/group-117/oracle_db_container-118/oracle_timeflow-119/datafile@oracle_snapshot-73
22:25:48 817M 196845 domain0/group-117/oracle_db_container-118/oracle_timeflow-119/datafile@oracle_snapshot-73
$ ls -lh /tmp/foo
-rw-r--r- 1 delphix staff 987M Jun 22 22:25 /tmp/foo
$

Replication of course always uses the -e and -c flags.

History

#1

Updated by Electric Monk about 2 years ago

  • % Done changed from 0 to 100
  • Status changed from New to Closed

git commit df477c0afa111b5205c872dab36dbfde391656de

commit  df477c0afa111b5205c872dab36dbfde391656de
Author: Paul Dagnelie <pcd@delphix.com>
Date:   2018-04-22T23:58:42.000Z

    9256 zfs send space estimation off by > 10% on some datasets
    Reviewed by: Matt Ahrens <matt@delphix.com>
    Reviewed by: John Kennedy <john.kennedy@delphix.com>
    Approved by: Richard Lowe <richlowe@richlowe.net>

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