Options for Dynamically Increasing LUN Sizes
Rob McNelly explains the process of mapping storage through VIOS to IBM i partitions
I am periodically brought in to work on systems where storage is mapped through VIOS to IBM i partitions.
There is a limit of 127 LUNs that can be presented to a virtual adapter.
If many small LUNs are allocated to an IBM i LPAR, you will find yourself in a situation where you can no longer add LUNs. Fortunately, it is simple enough to DLPAR and add an additional virtual adapter to VIOS and the IBM i partition so that you can add LUNs. In addition, there is an option to modify the LUN size on the SAN itself:
“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.
“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 load source.”
One final thing: The option to dynamically create/remove additional LUNs is also covered. So be sure to read the entire doc.
LinkedIn Newsletter Devoted to IBM Power and Related Topics
I recently became aware of Mike Davison’s weekly LinkedIn newsletter, the Power Socket. An IBM Champion, Mike’s most recent issue covered last week’s COMMON Europe conference. Prior to that, he linked to information about Power, storage, AIX, IBM i and more.
I always enjoy getting others’ perspectives about the goings-on in the Power ecosystem. This is another good resource that I’ll be reading regularly.
The jnetperf Utility
I was recently asked about getting iperf to run on an IBM i partition. Initially I thought I might be able to get it to run in PASE, but this thread brought me back to reality. Fortunately, I discovered jnetperf, a utility that “makes it possible to measure network throughput between two IBM i hosts (on same or different frames) or to/from Linux, AIX, Windows or any other platform that runs Java. To get best speed you need to use TCP and large packet sizes. The iperf tool defaults to 128K for TCP and 8K for UDP.”
OpenSSH Vulnerabilities Affect AIX, updateios Error
From IBM Support:
1) “In OpenSSH before 10.3, a file downloaded by scp may be installed setuid or setgid, an outcome contrary to some users’ expectations, if the download is performed as root with -O (legacy scp protocol) and without -p (preserve mode)…
“In OpenSSH before 10.3, command execution can occur via shell metacharacters in a username within a command line. This requires a scenario where the username on the command line is untrusted, and also requires a non-default configurations of % in ssh_config.”
Be sure to read the document, which has the complete list of CVEs. Check them all, and then check to see if you have the fixes installed on your system.
2) This APAR also caught my eye:
“During updateios from 4.1.1 to 4.1.2.00, error occurred during installation of ios.artex_profile.rte :
When updating to 4.1.2, if the artex.base.rte fileset is not applied before the os.artex_profile.rte, then there will be errors when the ios fileset is applied about missing attributes.”
IBM, Red Hat Announce New AI Initiative
IBM and Red Hat recently announced Project Lightwell. The multi-billion dollar project will involve more than 20,000 engineers worldwide, as explained in this press release:
“Project Lightwell will establish a trusted enterprise clearinghouse combined with a global force of engineers to identify and fix vulnerabilities at scale. The clearinghouse will serve as a security coordination layer, using advanced AI capabilities to validate and test fixes across an unprecedented volume of open source code. These capabilities will be offered through commercial subscriptions, allowing enterprises to integrate secure patches directly into their existing software supply chains with enterprise-grade validation and lifecycle management.
Open source software underpins modern enterprise infrastructure, with more than 90% of Fortune 500 companies relying on OSS. At the same time, advances in frontier AI are accelerating vulnerability discovery and exploitation. Anthropic recently reported that its Mythos Preview model identified nearly 3,900 high- or critical-severity vulnerabilities in open source software alone.”
For more, check out IBM’s Project Lightwell page:
“Project Lightwell is designed to resolve one of the hardest problems in enterprise software: fixing vulnerabilities without breaking what is already in production.
“Project Lightwell delivers validated fixes to the specific open source versions organizations already run. By combining large-scale engineering, AI, and a coordinated clearinghouse model, it enables organizations to move from detection to remediation without disrupting stability, certification, or compliance requirements.
- From detection to remediation
- From tools to platforms
- From fragmented fixes to coordinated trust
“When a vulnerability is identified, Project Lightwell backports fixes to the exact dependency versions already tested and deployed in production, delivering patched artifacts without requiring upgrades.
“No access to source code is required. Project Lightwell operates on dependency manifests such as pom.xml, ensuring your application code remains fully within your environment while patched artifacts are delivered to repositories you control.”
PS/2 Resurrected on YouTube
For a trip down memory lane, videos like this remind me just how far we have come. I am glad to see people resurrecting these old machines; I do not know if I would have the patience to do the same. Of course I remember using the IBM PS/2 when these machines were new and state of the art, and I still use a Model M keyboard as my daily driver. It is quite interesting watching a new generation become acquainted with this tech.