How to determine stripe size and stripe width on HPUX 11.11 for MBRC

From: Lou Avrami <>
Date: Thu, 04 Sep 2008 16:49:18 -0400 (EDT)
Message-Id: <>

Hello all,

I have inherited several Oracle data warehouses on HP-UX 11.11 servers, each 2+ TBs. All of them are experiencing various performance issues.

The db_multiblock_read_count (MBRC) on these databases are explicitly set to the value of 8. To try to get a better idea of what we might increase the MBRC to, I wanted to figure out the values for the formula:

     [stripe width] x [stripe size] / [db_block_size ]

How can I determine the values for stripe width and stripe size on HP-UX 11.11?

I thought perhaps the lvdisplay command might have the info. Looking at typical output, I see that there is a Stripe Size. Would Lv Size correspond to the stripe width?

$ lvdisplay /dev/vgdb/lvol1
--- Logical volumes ---

LV Name                     /dev/vgdb/lvol1
VG Name                     /dev/vgdb
LV Permission               read/write   
LV Status                   available/syncd           
Mirror copies               0            
Consistency Recovery        MWC                 
Schedule                    striped      
LV Size (Mbytes)            1198080         
Current LE                  4680      
Allocated PE                4680        
Stripes                     6       
Stripe Size (Kbytes)        1024                
Bad block                   NONE         
Allocation                  strict                    
IO Timeout (Seconds)        default             

I also looked at the vgdisplay command, part of which I have included below. Is there something here that is the equivalent of stripe size and stripe width?

  • Volume groups --- VG Name /dev/vgdb VG Write Access read/write VG Status available, exclusive Max LV 16 Cur LV 5 Open LV 5 Max PV 255 Cur PV 36 Act PV 36 Max PE per PV 65535 VGDA 72 PE Size (Mbytes) 256 Total PE 14364 Alloc PE 14364 Free PE 0 Total PVG 0 Total Spare PVs 0 Total Spare PVs in use 0
    • Logical volumes --- LV Name /dev/vgdb/lvol1 LV Status available/syncd LV Size (Mbytes) 1198080 Current LE 4680 Allocated PE 4680 Used PV 12 .... ....

I realize that perhaps the best way to determine the optimal MBRC value with these file systesm would be to use the dd command and write a large datafile with different block size options to the filesystems. These database though have been up and running for quite a while and it's not possible to quiesce the systems and run benchmarks.

If anyone could confirm what I should be looking at with lgdisplay or vgdisplay, or can suggest another command, it would be greatly appreciated.

Lou Avrami

Received on Thu Sep 04 2008 - 15:49:18 CDT

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