[comp.sys.hp] sar reporting incorrectly on 9000/822

s900387@minyos.xx.rmit.oz.au (Craig Macbride) (05/13/91)

A 9000/822 running version 7 HP/UX has an inode table of size over 600.
These days, sar reports the current size as _always_ between 0 and 4 less
than the _total_, no matter how many processes are running or how many files
are actually open! No overflows are recorded, nor do errors occur at any time.
The open file table is reported to be around 200/1100 most of the time, which
seems reasonable.

Do anyone know what may cause this strange behaviour?

-- 
 _--_|\		Craig Macbride	<uni: s900387@minyos.xx.rmit.oz.au>
/      \			<work: craig@bacchus.esa.oz.au>
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      v

notes@teecs.UUCP (Notes manager) (05/15/91)

/ teecs:comp.sys.hp / s900387@minyos.xx.rmit.oz.au (Craig Macbride) 

>A 9000/822 running version 7 HP/UX has an inode table of size over 600.
>These days, sar reports the current size as _always_ between 0 and 4 less
>than the _total_, no matter how many processes are running or how many files
>are actually open! No overflows are recorded, nor do errors occur at any time.
>The open file table is reported to be around 200/1100 most of the time, which
>seems reasonable.

>Do anyone know what may cause this strange behaviour?


This same problem exists on 825/835 systems running hp-ux 7.0.
When I first saw it, I assumed that the table was actually almost
full, so I increased its size, only to find that sar still showed it
to be almost full!  The lack of any overflow messages means that
it is sar at fault; the tables seem to be OK.  I assume it
is a bug in sar at hp-ux 7.0.

+-----------------------------------------------+-------------------------+
| Hershel Belkin               hp9000/825(HP-UX)| UUCP: teecs!belkin      |
| Test Equipment Engineering Computing Services |Phone: 416 249-1231 x2647|
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+-----------------------------------------------+-------------------------+

franks@hpuamsa.neth.hp.com (Frank Slootweg CRC) (05/16/91)

Re: This "bug" is actually a feature.

  The inode table is used for both open inodes and for used_to_be_open_
but_now_closed inodes. For open inodes it is a real table: If it is
full and a new inode must be opened it overflows. For ex-open inodes it
is a cache: I.e. old entries are kept untill a new inode must be opened
and there is no free entry.

  So like any good cache it is (nearly) full (nearly) all of the time
and that is what "sar" reports. I understand that HP proprietary (sp?)
programs like GlancePlus/UX will report both open and ex-open cached
inodes in future. I do not know if the UNIX standard bodies allow us to
add such features to the "sar" output.

  B.T.W. The open-file table is a table, not a cache, so if *it* is full
then no more files can be opened and the kernel will say so.

Frank Slootweg, HP, Dutch Customer Response Center.