IDS Forum

onstat -g iof: gfd and chunk number

Posted By: JACOB SALOMON
Date: Wednesday, 22 October 2014, at 6:13 p.m.

Greetings.

I am *SO* sure I have asked this question before but I can't locate it within the forum so here I go, perhaps again.

When I enter the command: onstat -g iof, the first line of each chunk's I/O stats looks something like this:

gfd pathname bytes read page reads bytes write page writes io/s
3 root_file 1548288 756 286720 140 626.0

(Sorry, I can't make the columns line up unless you paste the 2 lines into a text editor with a fixed-width font.)

There are two things missing from this output:
- The complete path of the chunk, which would avoid confusion in the unlikely
event of an admin creating identical symlinks in different directories
- An offset, which would distinguish multiple chunks created at different
locations within a raw character device file (or even cooked file). (I have
actually encountered this condition at a client and had to untangle their
setup. Fun project!)

A possible cure is to map the gfd (global file descriptor) above to a chunk number. I already have seen that if there is no gap in chunk numbers, the gfd is the chunk number + 2. However, this is not reliable; if there is a gap in the chunk numbers, e.g. chunk 5 had been dropped before the most recent engine bounce, this simple formula falls apart. Chunk[4] would be open as gfd[6] and chunk[6] would be open as gfd[7] (rather than gfd[8]).

(Ah, he finally gets to the point!)
Is there a totally reliable way to map a chunk's gfd number to its chunk number?

Thanks much!

-- Jacob (with the long-winded fingers :-)

Messages In This Thread

• onstat -g iof: gfd and chunk number
  JACOB SALOMON -- Wednesday, 22 October 2014, at 6:13 p.m.
  • Re: onstat -g iof: gfd and chunk number
    John Miller iii -- Wednesday, 22 October 2014, at 8:03 p.m.
    • Re: onstat -g iof: gfd and chunk number
      JACOB SALOMON -- Thursday, 23 October 2014, at 10:35 a.m.
      • Re: onstat -g iof: gfd and chunk number
        JON RITSON -- Thursday, 23 October 2014, at 11:11 a.m.
        • Re: onstat -g iof: gfd and chunk number
          JACOB SALOMON -- Thursday, 23 October 2014, at 1:32 p.m.

IDS Forum is maintained by Administrator with WebBBS 5.12.