Hi,
The snapshot reserve specifies a set percentage of disk space for snapshots.
By default, the snapshot reserve is 20% of disk space. The snapshot reserve can be used only by snapshots,
not by the active file system.
This means that if the active file system runs out of disk space,
any disk space still remaining in the snapshot reserve is not available for active file system use.
Snapshot reserve management involves the following tasks:
Ensuring that enough disk space is set aside for snapshots so that they do not consume active file system space
Keeping disk space consumed by snapshots below the snapshot reserve
Ensuring that the snapshot reserve is not so large that it wastes space that could be used by the active file system
When enough disk space is available for snapshots in the snapshot reserve,
deleting files in the active file system frees disk space for new files,
while the snapshots that reference those files consume only the space in the snapshot reserve.
If Data ONTAP created a snapshot when the disks were full,
deleting files from the active file system would not create any free space because everything
in the active file system would also be referenced by the newly created snapshot.
Data ONTAP would have to delete the snapshot before it could create any new files
Also use snap autodelete
You can define which Snapshot copies you delete by entering the following options and their values:
Use trigger option to define when to begin automatically deleting snapshots copies
here is the description:
trigger
Defines when to begin automatically deleting Snapshot copies.
volume--begin deleting Snapshot copies when the volume reaches 98% capacity and the volume snap reserve has been exceeded.
snap_reserve--begin deleting Snapshot copies when the Snapshot reserve reaches 98% capacity.
space_reserve--begin deleting Snapshot copies when the space reserved in the volume reaches 98% capacity and the volume snap reserve has been exceeded.
Check whether the Snap autodelete policy is setup correctly.
On ascertaining that the policy has not been removing the snapshots despite being setup correctly,
check the volume option try_first.
Type the following command from the filer command line interface: filer_cli> vol options
Output similar to the following is displayed:
test_lab_filer> vol options voltest
nosnap=off, nosnapdir=off, minra=off, no_atime_update=off, nvfail=off,
ignore_inconsistent=off, snapmirrored=off, create_ucode=on,
convert_ucode=on, maxdirsize=83886, schedsnapname=ordinal,
fs_size_fixed=off, compression=off, guarantee=volume, svo_enable=off,
svo_checksum=off, svo_allow_rman=off, svo_reject_errors=off,
no_i2p=off, fractional_reserve=0, extent=off, try_first=volume_grow,
read_realloc=off, snapshot_clone_dependency=off
By default, the volume option try_first is set to volume_grow.
However, this setting conflicts with the Snap autodelete policy and effectively results in no snapshots getting deleted.
Modify the option volume_grow to snap_delete using the following command from the filer command line:
filer_cli> vol options try_first snap_delete
From experience,
always monitor your system for functions like autodelete and autogrow when you deploy for first time
greetings
