VNX FILE SnapSure SAVVOL

Question

Hello, How VNX FILE SnapSure allocate SAVVOL space? How can I find it's usage?

HEAT1 · Accepted Answer

1. When first ckpt is created for a filesystem the system allocates SAVVOL space in same AVM pool as primary filesystem by default. SnapSure automatically:

Creates a SavVol by using the following criteria:

If PFS > 20 GB, then SavVol = 20 GB.
If (PFS < 20 GB) and (PFS > 64 MB), then SavVol = PFS size.
If PFS < 64 MB, then SavVol = 64 MB, which is the minimum SavVol size.

Monitors the SavVol, and if a checkpoint reaches a HWM of 90 percent (default), extends it to keep the checkpoint active or readable. The SavVol extends by 20 GB each time until the SavVol usage is below the HWM. If the SavVol was created manually (not using AVM), then it extends by 10 percent of the PFS size each time. The maximum SavVol size also affects the SavVol extension size. If the maximum SavVol size is set by the user, and extending another 20 GB would make the SavVol exceed the maximum size, then the extension size is adjusted to the maximum size minus the current size.

2. To find out the SAVVOL space usage you can get it from ckpt properties and follow the link on “Checkpoint Storage”.

Jeethendra_seth · Answer

Hi,

If the auto checkpoint creation is failing due to no space in SavVol, Can we expand the SavVol manually? If yes, how? I know that there is a parameter setting available in "nas_param" but that is for auto extension of SavVol.

Any inputs appreciated..

Thanks in advance.

Rainer_EMC · Answer

The savvol should auto-extend unless the pool is full or you set the max size or hit the system limit. yes you can extend manually with nas_fs -xtend Please see the 'Using SnapSure on VNX'

Jeethendra_seth · Answer

Thank you so much for confirmation.. This is one of most confusing part for SavVol

VNX

VNX FILE SnapSure SAVVOL

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