Max_io_size?

[Miguel A. Velasco Corte]

Hi,

How can i found out what the max_io_size is for my HPUX 11i?

Regards,

Miguel

[Helen French]

Hi Miguel:

From TKB #KBRC00003661:

PROBLEM

To tune Oracle it is required to know the maximum io transfer size. What is the maximum single io transfer size on a HP-UX system?

RESOLUTION
1) Using raw disk devices, the maximum io transfer size is 1 megabyte.

2) Using LVM (logical volume manager) the maximum io transfer size is 256
kbytes.

3) Using LVM with LVM striping, the maximum io transfer size is limited to the size of your strip or at most 256k.


The disk io drivers will also try to combine the requests, so it's possible to have a larger io transfer size, but since this is not easily calculated, there is no way to know what the highest io transfer size could be.

HTH,
Shiju

[harry d brown jr]

kmtune | grep maxdsiz

shows you how much memory a process can consume. Maybe you were looking for something else?

live free or die
harry

[IT Response]

Miguel

The right parameter is max_direct_iosz. This is a parameter belong to VxFS. If you want to tune it, then either using vxtunefs command or create a file /etc/vx/tunefstab, for example:

To display:

# vxtunefs -p /home
Filesystem i/o parameters for /home
read_pref_io = 65536
read_nstream = 1
read_unit_io = 65536
write_pref_io = 65536
write_nstream = 1
write_unit_io = 65536
pref_strength = 10
buf_breakup_size = 131072
discovered_direct_iosz = 262144
max_direct_iosz = 262144 <------ here
default_indir_size = 8192
qio_cache_enable = 0
max_diskq = 1048576
initial_extent_size = 8
max_seqio_extent_size = 2048
max_buf_data_size = 8192

Hope these info will help you further
Hoang