HPUX11.0 equivalent for MAX_IO_SIZE

[Frank de Vries]

I need to verify the value of
MAX_IO_SIZE which is an operating system dependant parameter.
I tried to find it using sysdef (in vain)
then I did a grep on /stand/build, again
did not see it.
Is there a equivalent or must I just add it first ? If so where ?
[root@orasrv2:]/stand/build<>>> grep -i MAX tune.h
#define DBC_MAX_PCT 8
#define SENDFILE_MAX 0
#define AIO_MAX 2048
#define AIO_LISTIO_MAX 256
#define AIO_PRIO_DELTA_MAX 20
#define MAXDSIZ 990056448
#define MAXSSIZ 0x00800000
#define MAXSWAPCHUNKS 4513
#define MAXTSIZ 0x04000000
#define MAXUPRC 512
#define MAXTHREADPROC 2048
#define MAXUSERS 128
#define MAXDSIZ_64BIT 0x0000000040000000
#define MAXSSIZ_64BIT 0x00800000
#define MAXTSIZ_64BIT 0x0000000040000000
#define MSGMAX 65535
#define SHMMAX 1073741824
#define NCLIST (100+16*MAXUSERS)
#define NETMEMMAX 0
#define NPROC (20+8*MAXUSERS)
#define MAXQUEUETIME 0
#define KSI_SEND_MAX 32
#define KSI_ALLOC_MAX (NPROC*8)
#define MAXFILES_LIM 4096
#define MAXFILES 4096
#define MAXVGS 10
#define MAX_ASYNC_PORTS 50
#define INITMODMAX 50
#define MODSTRMAX 500
#define MAX_FCP_REQS 512
#define VX_MAXLINK 32767
#define HFS_MAX_RA_BLOCKS 8
#define VXFS_MAX_RA_KBYTES 1024
#define SCSI_MAXPHYS 1048576
#define MAX_MEM_WINDOW 0
[root@orasrv2:]/stand/build<>>>
thanks

[Steven E. Protter]

My fuzzy recollection is that this is built into the kernel as a non-configurable parameter.

Kind of like the hard limit on the number of groups a user can be in.

SEP

[Frank de Vries]

It is not a problem for me as I have no intention to tune it anyway.
However I need to know its value though
for something else to configure correctly.
Any idea how I can verify to what
value it is set.
Tx.

[Steve Steel]

Hi

Look at

scsi_maxphys - maximum allowed length of an I/O on all SCSI devices


Steve Steel

[Frank de Vries]

You could be very right.
Our scsi_maxphys is set to 1048576
I presume that is bytes.
I will try that (will be monday)

[Jeff Schussele]

Hi Frank,

Yes - that's the equiv to your max_io_size.
But be aware that docs.hp.com shows the default to indeed be 1,048,576 and cautions that it should *never* be raised except on V-class system & then it can be raised to 32MB. And also should never be lowered.

Here's the descrip:

DESCRIPTION

This tunable sets the maximum data size the SCSI subsystem will accept for an I/O. Depending on the device's characteristics and the device driver configuration, the maximum size allowed by the SCSI subsystem for a particular SCSI device might be lower than or equal to this tunable's value. It will never be greater.

HTH,
Jeff

[Frank de Vries]

I don't want to change the parameter MAX_IO_SIZE, but during an installation of an application a value of one of its variables had to be set EQUAL to the value
of MAX_IO_SIZE, with the nice comment
to look at our OS manual for details.
(Yeah right)

I tried using the value of this scsi io
parameter you suggested.
Unfortunately to no avail.

I am going to log a call with the Application
vendor what exactly it means with MAX_IO_SIZE as this parameter does not exist under that name on HPUX11.00.

Live is tough.
And then you die °`)