03-03-2005
iostat -e / -E output explanation
Hi all, hope you are having a nice day, its nice and warm today in Canberra Australia.
iostat -e / -E reports soft and hard errors. Any idea what these are exactly? All I hear are I/O's failing and needing to retry, but no cause as to why they fail.
My SUN guru tells me its our EMC SAN array generating RSCN's or other fibre channle stuff, and the qlogic card then logs back into the fabric, and during that process some I/O has failed. However the iostat errors come up regardless of the EMC san.
I have searched for and read articles, etc, and really found nothing. however one article said the scsi driver doesn't know the disk RPM speed, another saying that SUN array software needs to be turned off.
We have a history with SUNmc causing SAN disk problems by constantly polling the disk for information (which is why we are upgrading it and have turned it off on some servers).
If you have lots of soft errors, are you likely to get a hard error? When you have lots of hard errors (eg, an internal disk is reporting 2400 hard errors with no corresponsing /var/adm/message entries to do with RSCN, scsi, etc) will you end up with track/cylinder errors?
I guess database/application issues will also cause I/O retries just like tcpip.
The number of network output/inpuit/collisions/queues, also do not relate to the iostat -e output.
Many Thanks
take care all
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LEARN ABOUT OPENSOLARIS
nice
nice(2) System Calls nice(2)
NAME
nice - change priority of a process
SYNOPSIS
#include <unistd.h>
int nice(int incr);
DESCRIPTION
The nice() function allows a process to change its priority. The invoking process must be in a scheduling class that supports the nice().
The nice() function adds the value of incr to the nice value of the calling process. A process's nice value is a non-negative number for
which a greater positive value results in lower CPU priority.
A maximum nice value of (2 * NZERO) -1 and a minimum nice value of 0 are imposed by the system. NZERO is defined in <limits.h> with a
default value of 20. Requests for values above or below these limits result in the nice value being set to the corresponding limit. A nice
value of 40 is treated as 39.
Calling the nice() function has no effect on the priority of processes or threads with policy SCHED_FIFO or SCHED_RR.
Only a process with the {PRIV_PROC_PRIOCNTL} privilege can lower the nice value.
RETURN VALUES
Upon successful completion, nice() returns the new nice value minus NZERO. Otherwise, -1 is returned, the process's nice value is not
changed, and errno is set to indicate the error.
ERRORS
The nice() function will fail if:
EINVAL The nice() function is called by a process in a scheduling class other than time-sharing or fixed-priority.
EPERM The incr argument is negative or greater than 40 and the {PRIV_PROC_PRIOCNTL} privilege is not asserted in the effective set of
the calling process.
USAGE
The priocntl(2) function is a more general interface to scheduler functions.
Since -1 is a permissible return value in a successful situation, an application wishing to check for error situations should set errno to
0, then call nice(), and if it returns -1, check to see if errno is non-zero.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |Async-Signal-Safe |
+-----------------------------+-----------------------------+
SEE ALSO
nice(1), exec(2), priocntl(2), getpriority(3C), attributes(5), privileges(5), standards(5)
SunOS 5.11 1 Apr 2004 nice(2)