卷 Snapshot 自动删除

适用于

• Data ONTAP 8
• ONTAP 9

问题

即使快照保留当前设置为 30 天，卷快照也会被自动删除。
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Snapshot autodelete settings for AUHVSNA1_SHARED:
                                        state=on
                                        commitment=try
                                        trigger=snap_reserve
                                        target_free_space=10%
                                        delete_order=oldest_first
                                        defer_delete=user_created
                                        prefix=(not specified)
                                        destroy_list=none =========================================
00000011.0010da6a 1b4cc5ac Tue Nov 25 2014 00:56:12  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'weekly.0' in volume 'AUHVSNA1_SHARED' to recover storage
00000011.0010da6c 1b4cc63c Tue Nov 25 2014 00:56:27  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'hourly.4' in volume 'AUHVSNA1_SHARED' to recover storage
00000011.0010da6e 1b4cc6d1 Tue Nov 25 2014 00:56:42  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'hourly.3' in volume 'AUHVSNA1_SHARED' to recover storage
00000011.0010da70 1b4cc758 Tue Nov 25 2014 00:56:55  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'hourly.1' in volume 'AUHVSNA1_SHARED' to recover storage
00000011.0010da72 1b4cc7f1 Tue Nov 25 2014 00:57:11  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'hourly.0' in volume 'AUHVSNA1_SHARED' to recover storage
00000011.0010da74 1b4cc888 Tue Nov 25 2014 00:57:26  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'nightly.0' in volume 'AUHVSNA1_SHARED' to recover storage
00000011.0010da76 1b4cc937 Tue Nov 25 2014 00:57:43  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'Dont_Delete_INC0752286' in volume 'AUHVSNA1_SHARED' to recover storage
00000011.0010da79 1b4cc9ab Tue Nov 25 2014 00:57:55  11:00 [disk.healthTrigger:warning] Disk 3a.42 received NHT health trigger (0x1 0xb 0x5d 0x5)
00000011.0010da7a 1b4cc9e9 Tue Nov 25 2014 00:58:01  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'Snapshot_4:45_24_11_2014' in volume 'AUHVSNA1_SHARED' to recover storage
00000011.0010da7c 1b4ccaa3 Tue Nov 25 2014 00:58:20  11:00 [wafl.volume.snap.autoDelete:info] Deleting snapshot 'Manual_snapshot' in volume 'AUHVSNA1_SHARED' to recover storage

As you can see here, On Nov 23, the volume /vol/AUHVSNA1_SHARED/ was at 96% capacity.  Something happened between Nov 23, and Nov 25 that pushed that volume to its capacity and snapshots were deleted on Nov 25 to save the volume.

Filesystem                         kbytes           used              avail    capacity  Mounted on
Nov 23
/vol/AUHVSNA1_SHARED/                               5653468812                 5424660856                  228807956      96%  /vol/AUHVSNA1_SHARED/
/vol/AUHVSNA1_SHARED/.snapshot             115376912                    87988840                      27388072      76%  /vol/AUHVSNA1_SHARED/.snapshot

Nov 25
/vol/AUHVSNA1_SHARED/                              5858989708                 5452568432                  406421276      93%  /vol/AUHVSNA1_SHARED/
/vol/AUHVSNA1_SHARED/.snapshot             119571216                    2969476                         116601740       2%  /vol/AUHVSNA1_SHARED/.snapshot
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最旧的快照首先根据选项的要求被删除，但为了保持卷处于活动状态，由于空间问题，它不断删除快照，即卷处于 96% 的容量，空间不足，并且快照不断删除，直到空间足够。 

当时发生了一些事情，将卷推送到容量，所有快照都被删除了。如果卷空间允许，删除过程将在一个快照处停止；但是，卷空间不允许。 

此外，target_free_space 设置为 10%，请参阅自动删除 Snapshot 副本

target_free_space：确定何时停止删除 Snapshot 副本。target_free_space 值是卷的某个百分比。例如，如果指定 20，则删除 Snapshot 副本，直到卷的 20% 为可用空间。

通常的做法是指定比自动删除阈值小 2% 的 target_free_space 值，以避免不必要地删除快照副本。