Anyone seen negative numbers on MB/s when preclearing drives?  Started out just fine then 20% in I refreshed and it started showing negative numbers.  I precleared a 2tb last night and all was fine but I was running 5.014b, today I upgraded to rc3 and started preclearing these 5 new ones and this happened, no array set up just these new drives.  Telnet screen shows correct positive numbers but unraid web shows negative.

ok I take that back, telnet does show correct positive MB/s but the estimated time is still negative numbers.

 

You likely had a time adjustment occur after you started preclear. Did you change the timezone?

nope, kicked it off and let it run.  I just went back and hit refresh to see where it was at.

I can see your logic and agree with you that a time adjustment of some sort could have happened behind the scenes but the MB/s isn't time related so why would it be negative.  I refreshed this morning and everything was back to normal.  I can't explain it, just wondered if anyone else had experienced it and if it was a bug....and if it was a bug where is it, unmenu or unraid or something else.

the MB/s isn't time related so why would it be negative.

 

Megabytes per second. A second is a unit of time. If you divide the number of MB processed by the time in seconds it took to do the processing, you get MB/s.

Agreed, it is a measurement of time, what I meant was if the system had a clock/time adjustment then I could see the time frame itself would change but MB/s shouldn't have anything to do with the clock, but I guess I could be wrong.  With this being a new server build I want to find out if something is wrong before I start adding drives to the array and loading data.

Lets go through this math lesson, and it could easily depend on when and how the software records the starting and ending time. If it does not take into account timezones then it could easily produce negative rates.

 

Question: What is your transfer rate? (In this case we have a clock-skew adjustment against NTP to adjust for the system being fast)

 

It's 10:00:01 when you start the transfer.

You transfer 100 megs.

It's 10:00:00 when you finish the transfer.

 

Answer: -100 MB/s

 

(transfer) / (end_time - start_time) = 100 / (10:00:00 - 10:00:01) = 100 / -0:00:01 = -100

 

Second situation this time taking into account timezones. In the middle of the transfer you change from EST (Eastern time) to PST (Pacific time).

 

It's 10:00:00 EST when you start.

You transfer 100 megs.

It's 07:00:01 PST when you finish.

 

It might possible use the following math to determine the MB/s rate: 100 / (07:00:01 - 10:00:00)