I run a recent node. The used disk space increases slowly but monotonously.
How is it possible that, some days, the used disk space is less than the previous day?
Used Space Calculation
Let’s say a storage node is holding 1 TB of data. On the satellite side tally is responsible for accounting. Tally finds 1 TB and takes into account how frequently it is running. If it runs every hour it will write down 1 TBh. At the end of the day, we have 24 TBh. If it runs every 8 hours it will write down 3 times 8 TBh. At the end of the day still, 24TBh.
For the following example, lets assume Tally needs 23 hours to run and will write down 23 TBh. On 23 days in a row the satellite will write down 23 TBh per day but on the 24th day, the satellite will finish tally early in the morning and on the same day finish a second run. For that day tally will write down 46 TBh.
Now that we have one day with 46 TBh it is time to talk about the storage node dashboard and what it should do with these numbers.
Actual Behavior
The storage node dashboard gets the 23 TBh and the 46 TBh results from the satellite. It prints these results into a graph. Included in that print out is the assumption that the 46 TBh result is for a 24h window. That assumption is wrong and so the graph will contain a spike while the storage node was holding 1 TB all the time.
Expected Behavior
23 TBh / 23 hours = 1 TB. 46 TBh / 46 hours = 1 TB. At any time the storage node could print out an accurate graph. All it needs to do is aksing the satellite what the time window for the 23 TBh and the 46 TBh was. Tally has noted the time window. The data for an accurate graph is available.
Optional: With the time window the storage node could print out 24TBh per day. The graph would be accurate at any time. The follow-up question would be why don’t we print 1 TB instead of 24 TBh. That would make the graph better to read outside the simple 1 TB example. However, in the first place, the graph needs to be correct regardless of the unit we use for it.
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So… if I understand, the inaccuracy is a known issue? And if so, is it looking to be fixed…?
It is very accurate. It is just displayed wrong.
Currently this has not the highest priority and I don’t expect it to get fixed soon.
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That’s fair I suppose since it isn’t anything major. Would be nice to see a tweak done to display it right 