It's Time to Upgrade to VIOS 3.x
VIOS 2.6 is going out of support—and every prior 2.x version is already out of support. It's time to upgrade to 3.x.
By Rob McNelly07/28/2020
Nigel Griffiths's comprehensive look at VIOS 3.1 features good information about upgrading your VIO servers. You'll also find presentation slides and links to IBM documentation.
On that note, you should be aware of potential issues surrounding specific VIOS versions when you do an update or a 2.x to 3.x upgrade:
HIPER APAR IJ25390
Systems running the AIX 7200-04-02-2015 or 7200-04-02-2016 Technology Level or VIOS 18.104.22.168 or 22.214.171.124 with devices.vdevice.IBM.l-lan.rte below the 126.96.36.199 level.
The Virtual Ethernet Adapter can cause a significant degradation in TCP performance for largesend packets.
This issue can be seen with VIOS (serving any AIX®, IBM i, or Linux client LPAR) running the affected VIOS levels below. It can also be seen with any AIX client LPAR running the affected AIX levels below (regardless of the VIOS level). This issue only occurs when the client LPARs are configured for largesend traffic or VIOS is configured for largereceive traffic.
Install APAR IJ25390.
Prior to fix availability, an interim fix is available from either:
The iFix can be installed using Live Update (LU). If LU is not used, installation of the iFix requires a reboot.
Either disable mtu_bypass:
# chdev -l enX -a mtu_bypass=off
or disable PLSO on the VEA or trunk VEA:
# chdev -l entX -a platform_lso=no
Thanks to Chris Gibson, who gave me a heads up about this issue some weeks back.
Rob McNelly is a senior AIX solutions architect doing pre-sales and post-sales support for IBM Premier Business Partner Meridian IT Inc.