Overview

As of the DXi 2.2.1 software release, the way disk usage is displayed in the DXi user interface has changed. This has created confusion for our customers on how to interpret what the user interface reports as well as causing undue concern about running out of space.

 

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Problem

Pre-2.2.1 Data Usage Statistics	2.2.1 and Later Data Usage Statistics
Available	Available
Used	Used
Data Reduction	Data Before Reduction
	Data After Reduction

   

 

• The “Used” data is the same in both versions, no change there. 
• In 2.2.1, the “Data Reduction” data has been broken down into ”Data Before Reduction” and “Data After Reduction” for more granularity. 
• The “Available” data has changed in 2.2.1. Instead of just listing "Free" space, it now shows “Free Space” and “Reclaimable Space” and this was done to account for changes to the way space reclamation works.

In the pre-2.2.1 versions of the user interface, you could simply look at "Available" space and see how much space was left on the system.  Likewise, you could look at "Used" space and see how much space was used up. If you added the two values together they would total 100% of system capacity, as expected.

 

In the new version, if you add “Available” space and “Used” space you get a number much higher than expected. In the screenshot below, you see it comes out to 120.84% or 129TB when it is only a 107TB system.  Many customers have been confused by this.

 

The “Reclaimable” space is the culprit, because it is factored into both “Available” space and "Used" space.  It is available to be reclaimed, as needed, when the system runs low on “Free” space. This makes it available. The catch is that it is also added to the total “Used” space because it hasn't been reclaimed yet. 

 

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Solution

The Disk Usage display was a design choice to show how much space is allocated to the different states. There are various ways to think about the numbers to get a clear picture.

 

One way is to subtract the amount of “Reclaimable” space from the amount of “Used” space to get a true picture of the amount of disk space used.

 

Another way is to look at “Available” space as a whole and ignore the “Free” space.  When looking at just the “Free” space like we did in pre-2.2.1 software, the system may appear to be running out of space until you add in the “Reclaimable” space as well. So it's easier to look at the total amount of “Available” space.

 

What you don't want to do is add "Available" space and "Used" space and expect to get an accurate tally.

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User Interface Disk Usage Examples

Pre 2.2.1

 

 

 

2.2.1 and Later Software