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I am new to running a linux server and wanted to know the difference between the total memory shown with the top command (which appears to be 78GB)

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and the free command which shows that I have 743GB of memory

enter image description here

Thank you in advance!

CyberStems
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  • Welcome to the site. Please don't post [screenshots of console output](https://unix.meta.stackexchange.com/questions/4086/psa-please-dont-post-images-of-text). They are often difficult to read, the content will not show up in search enginre results, and contributors trying to help will have to type-copy content when trying to analyze/reproduce your problem. Instead, paste it into the question using code formatting. – AdminBee Feb 04 '21 at 08:10

1 Answers1

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top's free figure is 90G. There are + signs next to the total, used and buff/cache values. top reports the same sizes as free.

See the top manual page, in particular the description of the interactive E command in section 4a:

      E  :Enforce-Summary-Memory-Scale in Summary Area
          With this command you can cycle through the available
          summary area memory scaling which ranges from KiB
          (kibibytes or 1,024 bytes) through EiB (exbibytes or
          1,152,921,504,606,846,976 bytes).

          If you see a `+' between a displayed number and the
          following label, it means that top was forced to truncate
          some portion of that number.  By raising the scaling
          factor, such truncation can be avoided.
berndbausch
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  • Thanks for your answer berndbaush, can you kindly elaborate upon what you mean by "top's free figure"? I've summed the swap, total and buff/cache memory but they do not equate to 743GB - not sure if I misunderstood how top reports the same sizes as free. Lastly I do not see the -E option for the top command. I greatly appreciate any further insights you can provide in helping me become a better linux user! – CyberStems Feb 04 '21 at 20:24
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    By "top's free figure" I mean the amount of free memory reported by top. In your screenshot, *buffer cache* is 452GB, *used* is 235GB, *free* is 90, *total* is 780GB. Finally, `E` is not an option but an interactive command, which you use while `top` is running. – berndbausch Feb 05 '21 at 00:01