IBM Support

How to determine the byte sector size of a disk unit

Question & Answer


Question

How to determine if the byte sector size of a disk unit is 512 bytes, 520 bytes, 4096 bytes, or 4160 bytes?

Cause

Determining the sector size of a disk unit may be required to calculate converted sizes, performance, or determining required PTFs.

Examples:

- N1012304: How to Calculate the Size of Virtual Disks

- N1019845: SAS Adapter Performance Boost with VIOS

- MA46503: Image catalog install on vios 520 byte load source disk

- N1020957: PTF listing for 4096 disk sector support at 7.2 and 7.3

Answer

Using the DUMPLD macro in Service Tools will verify the byte sector size of a disk unit.
1. STRSST and sign in
2. Option 1. Start a service tool
3. Option 4. Display/Alter/Dump
4. Option 1. Display/Alter storage
5. Option 2. Licensed Internal Code (LIC) data
6. Option 14. Advanced analysis
7. Enter the following data:
1 DUMPLD
Press Enter
8. Enter the following data where 'x' is the unit number. Usually 1 is the load source:
Options . . . . . -unit x
Press Enter

The output will be similar to the one below. If all of the byte sectors have a value of FALSE, then 520-byte sectors are used.
*Note: 4K (4096 and 4196) are not displayed for IBM i 7.1 and lower


Display Formatted Data
Page/Line. . . 1 / 1
Columns. . . : 1 - 78
Find . . . . . . . . . . .
....+....1....+....2....+....3....+....4....+....5....+....6....+....7....+...
DISPLAY/ALTER/DUMP
Running macro: DUMPLD -UNIT 1
============================================================================
GENERAL INFO:
LogicalDasd Ptr = C00000FAD1003000 Unit Number = 1 Asp = 1
Low Use Ptr = C00001248E2F2780
OpController state is Operational (0x00)
Outstanding I/O = 0x00000000
Delayed I/O = 0x0000
V7R3M0 drv0
Size in pages = 0x0370EEF8
Has 512-byte sectors = FALSE
Has 4096-byte sectors = FALSE
Has 4160-byte sectors = FALSE
Is encrypted = FALSE
Thin Provisioned = FALSE
Has 4096-byte sectors = FALSE
Has 4160-byte sectors = FALSE
Is encrypted = FALSE
Thin Provisioned = FALSE
Protected by Mirror Hot Spare = FALSE
Remote Write Serialization Count = 0
Current LD State Info:
08/23/1928 12:03:24.6 State/Event: SOOPERAT
Is SSD = FALSE
HRI Object Ptr = C00001248E2F1000
Resource name = DMP027
Resource type = 19A1
Resource model = 099
This is SmLogicalDasdSolo.
--------------------------------------------------------------------------
IoHwDevDasd Ptr = C00001C2C41E2000
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Document Information

Modified date:
11 October 2024

UID

nas8N1022501