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D.Zou
Asked: 2016-04-15 19:52:15 +0800 CST

man page of swapon doesn't match with what I am seeing

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I am playing around with swap and added my own swap partition. but when I do I noticed something odd.

test@ubuntu:~/5Gdisk$ cat /proc/swaps
Filename   Type            Size    Used    Priority
/dev/sda5  partition       4192252 0       -1
/dev/sdb2  partition       5242876 0       -2

and my /etc/fstab

UUID=<bla bla> none  swap sw 0 0
/dev/sdb2      swap  swap sw 0 0

sdb2 is the swap partition that I added. I also checked the man page of swapon, and it says for priority it should be from -1 to 32767. So why does my swap parition has a priority of -2?

This is ubuntu 15. Thanks

partitioning

1 Answers

  1. Best Answer

    From man swapon it reads:

       -p, --priority priority
          Specify the priority of the swap device.  priority  is  a  value
          between  0  and  32767. Higher numbers indicate higher priority.
          See swapon(2) for a full description  of  swap  priorities.  Add
          pri=value  to the option field of /etc/fstab for use with swapon
          -a.

    so, that means in your /etc/fstab you would have your lines read as follows:

    UUID=<bla bla> none  swap sw,pri=20 0 0
/dev/sdb2      none  swap sw,pri=10 0 0

    I just used the priorities of 20 for the first one since it reads that the "Higher numbers indicate higher priority" in the manpage, then 10 for the lower priority. Options in the /etc/fstab file are separated by commas ,.

    Technically, -1 is higher than -2 so you are probably OK.

    Hope this helps!

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