Data Domain GUI Mtree 'Daily Written' may show both Active and Cloud tier ingestions when there are data-movement activities

Summary: Some customers may rely on GUI Data management-->Mtree -->'Daily Written' numbers to check their backup size, this is not accurate when there is data-movement on the same mtree as the diagram may show both Active and Cloud tier injestions, hence both backup and data-movement would be counted in resulting to misleading number for backup alone statistics. ...

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Symptoms

1. Data-movement was run against mtree /data/col1/avamar-1643691765 at Aug 26 
Data-movement was started on Aug 26 2023 18:07 and completed on Aug 26 2023 18:12
Moved (post-comp): 7.88 GiB, (pre-comp): 17.39 GiB,
Files inspected: 5049, Files eligible: 11, Files moved: 11, Files failed: 0

2. From GUI screenshot below, it appears around 52.2GiB data got written to Mtree /data/col1/avamar at 26 Aug:
image.png

3. Mtree show compression has more details on this, it shows clearly that the 52.2GiB contains both backup data (35GiB) and Data-movement data (17.4GiB).

As backup and data-movement occurred on the same mtree, if only looking at the number displayed in GUI 'Daily Written', it may get mis-interpreted that 52.2GiB is the backup size to such mtree at 26 Aug.

sysadmin@dd03# mtree show compression /data/col1/avamar-1643691765 start 2023/08/26 end 2023/08/27

From: 2023-08-26 12:00 To: 2023-08-27 12:00

Active Tier:
                                  Pre-Comp   Post-Comp   Global-Comp   Local-Comp      Total-Comp
                                     (GiB)       (GiB)        Factor       Factor          Factor
                                                                                    (Reduction %)
-------------------------------   --------   ---------   -----------   ----------   -------------
Written:
  From 2023-08-26 To 2023-08-27       52.2         8.0          3.5x         1.9x     6.6x (84.7)
  Last 24 hrs                         35.0         0.1        286.4x         1.5x   434.5x (99.8)
-------------------------------   --------   ---------   -----------   ----------   -------------
Cloud Tier:
                                  Pre-Comp   Post-Comp   Global-Comp   Local-Comp      Total-Comp
                                     (GiB)       (GiB)        Factor       Factor          Factor
                                                                                    (Reduction %)
-------------------------------   --------   ---------   -----------   ----------   -------------
Written:
  From 2023-08-26 To 2023-08-27       17.4         7.9          1.2x         1.9x     2.2x (54.7)
  Last 24 hrs
-------------------------------   --------   ---------   -----------   ----------   -------------

Cause

This could be a day one issue, Engineering team is still investigating on the cause and working on a fix.

Resolution

Do not rely on GUI Mtree 'Daily Written' as a backup size indicator while there is Data-movement  occurring on the same mtree.

When a mtree is configured for Data-movement, from DD CLI or ASUP, check 'mtree show compression' for the period you are interested to understand if the total 'Pre-comp GiB' in GUI 'Daily Written' has data-movement part included, minus it for backup size.

Data Domain Engineering is still investigating and working on a fix upon the moment this KB is published.

Affected Products

Data Domain
Article Properties
Article Number: 000217657
Article Type: Solution
Last Modified: 28 Nov 2023
Version:  3
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