First off, alert list member Michael Stapleton pointed
out that the value of shmmax was 12G. I adjusted that
down to ~1.6G (.8*2G) and after some reading, I also
set shmmin to 1 and rebooted.
A curious thing happened after that. When I do an ipcs -a
along with "Message Queue not in system" and the expected
info for shared memory, now I get "Semaphore facility not
So I submitted this to Sybase support. Here is a summary
of that exchange:
Questions to Sybase:
1 - given that Sybase is running on a multiprocessor
machine, why is the message queue module not being
loaded? (I notice also that the semaphores module
is also not loaded even though there are "set" commands
in /etc/system for them but that, I believe, is a
different problem unless you can shed some light on
it as well for me.)
2 - when this server was set up, the values for the
"set" commands were obtained (according to the people
I asked here) from Sybase. I'd like to know how the
numbers for shared memory and semaphores were arrived
at so that I can scale them if/when needed.
Summary of Answers from Sybase:
1 - Sybase does not use semaphores or message queues.
The only other kernel parameter they say they set besides
shmmax is shmseg (shared memory segments). This is set
based on the number of stripes used by Sybase to dump/load
data. Each stripe requires 1 shared memory segment.
2 - The shmmax value in /etc/system must be >= the value
entered for the configured for shared memory in Sybase.
As far as scaling goes, they say that each connection uses
70K of Sybase's memory and the math is linear
(1000 users = 1000*70K = 70M).
It seems a little strange to me that Sybase doesn't use semaphores
and even though they are "set" in /etc/system they don't show up
in ipcs -a but at least now if we have problems with the server we
can tell Sybase that we did what they told us to do.
Any DBAs out there with any comments?
-- Paul Kloepfer email: firstname.lastname@example.org Sr. UNIX Admin phone: 202-261-2625 Enews.com fax: 202-466-2565 http://www.enews.com - Your Online News Stand -
> -----Original Message----- > From: Kloepfer, Paul [mailto:email@example.com] > Sent: Tuesday, June 27, 2000 04:36 PM > To: 'firstname.lastname@example.org' > Subject: IPC Question > > > > Hi All. > > This is a little long but... > > E3500, 4x336MHz, 2G RAM, Solaris 2.6, Sybase 11.9.5 > > I'm working on improving the performance of the above > Sybase server. One of the things I looked into was IPC > settings and I noticed that the message queue module was > not loaded. > > Now, I seem to recall admining an SGI Challenge box running > Sybase that made use of message queues. > > I have our DBA talking to Sybase about this but I thought I'd > throw it out here too. > > I'm also a little concerned about the lack of semaphore > information from 'ipcs -a' below, but I have the DBA > checking into the Sybase suggested tunable settings for > that. > > Thanks. I will summarize. > Paul > -- > Paul Kloepfer email: email@example.com > Sr. UNIX Admin phone: 202-261-2625 > Enews.com fax: 202-466-2565 > http://www.enews.com > - Your Online News Stand - > > Here is some other info: > > db-va1.enews.com % ipcs -a > IPC status from <running system> as of Tue Jun 27 14:42:53 2000 > Message Queue facility not in system. > T ID KEY MODE OWNER GROUP > CREATOR CGROUP > NATTCH SEGSZ CPID LPID ATIME D TIME CTIME > Shared Memory: > T ID KEY MODE OWNER GROUP > CREATOR CGROUP > NSEMS OTIME CTIME > Semaphores: > db-va1.enews.com % > > db-va1.enews.com % tail -20 /etc/system > * To set a variable named 'debug' in the module named > 'test_module' > * > * set test_module:debug = 0x13 > > set shmsys:shminfo_shmmax=12349796224 > set semsys:seminfo_semmap=64 > set semsys:seminfo_semmni=4096 > set semsys:seminfo_semmns=4096 > set semsys:seminfo_semmnu=4096 > set semsys:seminfo_semume=64 > set shmsys:shminfo_shmmin=100 > set shmsys:shminfo_shmmni=100 > set shmsys:shminfo_shmseg=100 > * vxvm_START (do not remove) > forceload: drv/vxdmp > forceload: drv/vxio > forceload: drv/vxspec > * vxvm_END (do not remove) > * forceload: drv/esp > * set scsi_options=0x58 > db-va1.enews.com % > > db-va1.enews.com % sysdef | tail -34 > * > * IPC Messages > * > 0 entries in msg map (MSGMAP) > 0 max message size (MSGMAX) > 0 max bytes on queue (MSGMNB) > 0 message queue identifiers (MSGMNI) > 0 message segment size (MSGSSZ) > 0 system message headers (MSGTQL) > 0 message segments (MSGSEG) > * > * IPC Semaphores > * > 64 entries in semaphore map (SEMMAP) > 4096 semaphore identifiers (SEMMNI) > 4096 semaphores in system (SEMMNS) > 4096 undo structures in system (SEMMNU) > 25 max semaphores per id (SEMMSL) > 10 max operations per semop call (SEMOPM) > 64 max undo entries per process (SEMUME) > 32767 semaphore maximum value (SEMVMX) > 16384 adjust on exit max value (SEMAEM) > * > * IPC Shared Memory > * > 3759861632 max shared memory segment size (SHMMAX) > 100 min shared memory segment size (SHMMIN) > 100 shared memory identifiers (SHMMNI) > 100 max attached shm segments per process (SHMSEG) > * > * Time Sharing Scheduler Tunables > * > 60 maximum time sharing user priority (TSMAXUPRI) > SYS system class name (SYS_NAME) > db-va1.enews.com % > > > > > S > U BEFORE POSTING please READ the FAQ located at > N ftp://ftp.cs.toronto.edu/pub/jdd/sun-managers/faq > . and the list POLICY statement located at > M ftp://ftp.cs.toronto.edu/pub/jdd/sun-managers/policy > A To submit questions/summaries to this list send your > email message to: > N firstname.lastname@example.org > A To unsubscribe from this list please send an email message to: > G email@example.com > E and in the BODY type: > R unsubscribe sun-managers > S Or > . unsubscribe sun-managers firstname.lastname@example.org > L To view an archive of this list please visit: > I http://www.latech.edu/sunman.html > S > T >
S U BEFORE POSTING please READ the FAQ located at N ftp://ftp.cs.toronto.edu/pub/jdd/sun-managers/faq . and the list POLICY statement located at M ftp://ftp.cs.toronto.edu/pub/jdd/sun-managers/policy A To submit questions/summaries to this list send your email message to: N email@example.com A To unsubscribe from this list please send an email message to: G firstname.lastname@example.org E and in the BODY type: R unsubscribe sun-managers S Or . unsubscribe sun-managers email@example.com L To view an archive of this list please visit: I http://www.latech.edu/sunman.html S T
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