Assessing physical placement of data with the lslv command

Edit online

If the workload shows a significant degree of I/O dependency, you can investigate the physical placement of the files on the disk to determine if reorganization at some level would yield an improvement.

To see the placement of the partitions of logical volume hd11 within physical volume hdisk0, use the following: 
# lslv -p hdisk0 hd11
hdisk0:hd11:/home/op
USED  USED  USED  USED  USED  USED  USED  USED  USED  USED     1-10
USED  USED  USED  USED  USED  USED  USED                      11-17

USED  USED  USED  USED  USED  USED  USED  USED  USED  USED    18-27
USED  USED  USED  USED  USED  USED  USED                      28-34

USED  USED  USED  USED  USED  USED  USED  USED  USED  USED    35-44
USED  USED  USED  USED  USED  USED                            45-50

USED  USED  USED  USED  USED  USED  USED  USED  USED  USED    51-60
0052  0053  0054  0055  0056  0057  0058                      61-67

0059  0060  0061  0062  0063  0064  0065  0066  0067  0068    68-77
0069  0070  0071  0072  0073  0074  0075                      78-84
Look for the rest of hd11 on hdisk1 with the following: 
# lslv -p hdisk1 hd11
hdisk1:hd11:/home/op
0035  0036  0037  0038  0039  0040  0041  0042  0043  0044    1-10
0045  0046  0047  0048  0049  0050  0051                     11-17

USED  USED  USED  USED  USED  USED  USED  USED  USED  USED   18-27
USED  USED  USED  USED  USED  USED  USED                     28-34

USED  USED  USED  USED  USED  USED  USED  USED  USED  USED   35-44
USED  USED  USED  USED  USED  USED                           45-50

0001  0002  0003  0004  0005  0006  0007  0008  0009  0010   51-60
0011  0012  0013  0014  0015  0016  0017                     61-67

0018  0019  0020  0021  0022  0023  0024  0025  0026  0027   68-77
0028  0029  0030  0031  0032  0033  0034                     78-84

From top to bottom, five blocks represent edge, middle, center, inner-middle, and inner-edge, respectively.

  • A USED indicates that the physical partition at this location is used by a logical volume other than the one specified. A number indicates the logical partition number of the logical volume specified with the lslv -p command.
  • A FREE indicates that this physical partition is not used by any logical volume. Logical volume fragmentation occurs if logical partitions are not contiguous across the disk.
  • A STALE physical partition is a physical partition that contains data you cannot use. You can also see the STALE physical partitions with the lspv -m command. Physical partitions marked as STALE must be updated to contain the same information as valid physical partitions. This process, called resynchronization with the syncvg command, can be done at vary-on time, or can be started anytime the system is running. Until the STALE partitions have been rewritten with valid data, they are not used to satisfy read requests, nor are they written to on write requests.

In the previous example, logical volume hd11 is fragmented within physical volume hdisk1, with its first logical partitions in the inner-middle and inner regions of hdisk1, while logical partitions 35-51 are in the outer region. A workload that accessed hd11 randomly would experience unnecessary I/O wait time as longer seeks might be needed on logical volume hd11. These reports also indicate that there are no free physical partitions in either hdisk0 or hdisk1.