I/O performance in HPUX file systems Post: 302351224

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Top Forums UNIX for Dummies Questions & Answers I/O performance in HPUX file systems Post 302351224 by TonyFullerMalv on Monday 7th of September 2009 05:24:10 PM

09-07-2009

Registered User

Quote:

Originally Posted by Davinzy

HI Tony,
how can I check how many physical volumes are there ?

From what I remember you run:
# df -k .
in the data volume to determine the logical volume (LV) it is stored in.

# lvdisplay -v lvnn
where lvnn is the name and number of the LV your data is stored in to see what volume group your LV is part of.

# vgdisplay vgnn
where vgnn is the name and number of the volume group (VG).

This will tel you how many Physical Volumes (PVs) your VG is spread over, they could be slices of disks some on the same disk just top confuse matters and the VGs could be divided into several LVs but hopefully your system is using whole disks and the VG is dedicated to the LV your data is stored in!

I hope that helps?

Edit:
I should have said that by the sounds of what you say you do need the volume striped over as many disks as possible to get the best bandwidth and access time for your parallel processing on multiple small files.

Last edited by TonyFullerMalv; 09-07-2009 at 07:27 PM..

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nswapfs

nswapfs(5)							File Formats Manual							nswapfs(5)

NAME

       nswapfs - maximum number of file systems that can be enabled for swap

VALUES

   Default
   Allowed values
DESCRIPTION

       File  system  swap  devices  are  managed in a table for easier indexing in the kernel.	sets the kernel variable responsible for the upper
       limit on this table, and thus the upper limit to file systems which can be used for swap.

   Who is Expected to Change This Tunable?
       Anyone.

   Restrictions on Changing
       Changes to this tunable take effect at the next reboot.

   When Should the Value of This Tunable Be Raised?
       If another file system swap is added to the system which would increase the number above then returns to the caller (see the swapon(2) man-
       page).

   What Are the Side Effects of Raising the Value?
       More  file  systems  for swap can be added to the system, and the kernel will need a little more memory for the table.  A small performance
       side effect of the kernel having to scan more file systems to check for a duplicate during swapon is also true, but realistically  negligi-
       ble.

   When Should the Value of This Tunable Be Lowered?
       Only  if  you  are  sure  the system will never go over a certain number of swap file systems, and you wish to lower this tunable to save a
       small amount of kernel memory and kernel performance during swapon operations.

   What Are the Side Effects of Lowering the Value?
       No side effects other than the primary and presumably desired new limitation on the number of swap file systems.

   What Other Tunable Values Should Be Changed at the Same Time?
       None.

WARNINGS

       All HP-UX kernel tunable parameters are release specific.  This parameter may be removed or have its meaning changed in future releases	of
       HP-UX.

       Installation  of  optional  kernel  software, from HP or other vendors, may cause changes to tunable parameter values.  After installation,
       some tunable parameters may no longer be at the default or recommended values.  For information about the effects of installation  on  tun-
       able  values,  consult  the documentation for the kernel software being installed.  For information about optional kernel software that was
       factory installed on your system, see at

AUTHOR

       was developed by HP.

							     Tunable Kernel Parameters							nswapfs(5)