Product Documentation
Abstract
Starting in 7.3 TR3 (and later releases), the size of a configured SAN disk unit can be increased dynamically on Spectrum Virtualize based storage products (such as SVC, V7000, etc.)
Starting in 7.3 TR7 and 7.4 TR1 (and later releases), the size of a configured SAN disk unit can be increased dynamically on DS8900.
Content
Increase of virtual LUN size after initial allocation
External storage systems have the capability to increase a LUN size after its initial allocation. In the past, IBM i has not viewed any increase in a LUN’s size on an external storage system. Additional LUNs needed to be added to increase the capacity of a logical partition.
With IBM i 7.3 TR3 (and later releases), IBM i will recognize that an increase has occurred for Spectrum Virtualize based storage products. After an IPL, will allow the LUN to be used at its newly increased size.
As of 7.3 TR7 & 7.4 TR1 (and later releases), IBM i now supports the changing of the size of a LUN that comes from a DS8900 storage controller. If the LUN type on a DS8900 is a variable LUN size (models 050 and 099), that LUN can increase in size.
The IBM i host will not fully recognize the size change immediately, yet begins processing to prepare the internal structures for the size increase. After the next IPL, the full capacity of the new LUN size is usable. This can be utilized on all disks, including the the load source.
*Note: If you need additional storage added immediately, then an option is to create an additional LUN which can be added dynamically to the ASP (as long as there are enough available disk paths remaining - 127 maximum per port or virtual adapter). After the IPL for the increased lun size, the new lun can be removed dynamically from the ASP if desired.
Adding disk units to an existing auxiliary storage pool
https://www.ibm.com/docs/en/i/7.5?topic=pools-adding-disk-units-existing-asp
Removing a disk unit from an auxiliary storage pool
https://www.ibm.com/docs/en/i/7.5?topic=pools-removing-disk-unit-from-asp
Additional details -
- LUNs formatted with 4096 byte sectors will not change size. Dynamic increase of LUN size is only supported for 512, 520 and 4160 byte sector formats.
- Reduction of LUN size is NOT supported.
- If a mirrored LUN is increased, the change will not be recognized by IBM i even after an IPL. For IBM i to recognize an increase in the size of a mirrored LUN, do the size increase and then stop mirroring on IBM i, IPL IBM i past storage management recovery for the new larger size to be recognized, and then start mirroring again.
- The System Service Tools Advanced Analysis command GETDILSSTATUS will show if a LUN size change is in progress:
GETDILSSTATUS: DISPLAY/ALTER/DUMP Running macro: GETDILSSTATUS Dynamically Increasing Size For Unit: 0x32 Increasing from 0x238E38E to 0x2EAAAAA IPL needed to complete. Dynamically Increasing Size For Unit: 0x1A Increasing from 0x238E38E to 0x2EAAAAA IPL needed to complete. Dynamically Increasing Size For Unit: 0x1 Increasing from 0x238E38E to 0x2EAAAAA IPL needed to complete. There are 3 units ready.
- If the system is IPL'd before the additional storage has been initialized, it will resume initialization after the IPL has gone through SM recovery, and will require another IPL after the initialize is complete in order for the OS to show and use the larger size. Use GETDILSSTATUS to check before an IPL.
- The following LIC log entries may be associated with increasing LUN size:
| Major-Minor | Description |
| 1000-5111 | Data needed to be moved and completed successfully |
| 1000-5112 | Data needed to be moved, but failed to move |
| 1000-5113 | Initialization of the additional storage completed successfully |
| 1000-5114 | Initialization of the additional storage failed |
1a. IBM i 7.4 - Technology Refresh 1 needs to be applied. MF66481 is recommended.
1b. IBM i 7.3 - Technology Refresh 7 and PTF MF68678 need to be applied. MF66474 is recommended.
1c. IBM i 7.2 and below - Dynamic Lun Expansion is not supported. Volume will need to be removed from ASP, unmapped, increased, remapped, re-added to ASP.
2) Expand source and target node LUN's on storage.
3) Ensure that the iASP is Varied On and Available at the source node to allow the volume to be prepared.
DSPASPSTS ASPDEV(xxxxx), where ASPDEV is the iASP device which can be found with WRKASPCPYD command.
If the iASP is not varied on, then use the following command where xxxxx is the iASP device:
VRYCFG CFGOBJ(xxxxx) CFGTYPE(*DEV) STATUS(*ON)
4) Allow prepare to complete on source - this can be monitored with getdilsstatus macro:
4a. STRSST and sign in
4b. Option 1. Start a service tool
4c. Option 4. Display/Alter/Dump
4d. Option 1. Display/Alter storage
4e. Option 2. Licensed Internal Code (LIC) data
4f. Option 14. Advanced analysis
4g. Enter the following data:
1 getdilsstatus
Press Enter
4h. Leave the Options as [blank] and press Enter
5) Vary off the source node iASP and then vary back on the source node iASP to complete the disk expansion on the source node:
VRYCFG CFGOBJ(xxxxx) CFGTYPE(*DEV) STATUS(*OFF)
VRYCFG CFGOBJ(xxxxx) CFGTYPE(*DEV) STATUS(*ON)
6) IPL the target node for storage management to repopulate the target node disk sizes.
*Note: without completing this step, the flashcopy will fail.
7) Perform the iASP Flash Copy - Vary on of target iASP is expected to complete normally and additional prep is not needed since its copied from the source.
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Document Information
Modified date:
26 January 2024
UID
ibm10716777