z/vm Service Critical Issues

Transcription

1 z/vm Service Critical Issues Operating System Software Red Alerts December 16, 2013 z/vm Service Manager Contact: Jim McCormick IBM Corporation z/vm Development 1701 North Street Endicott, NY

2 December 2013 FIRMWARE UPGRADE MAY CAUSE A LOSS OF ACCESS TO DATA. Certain DS8100/DS8300/DS8700 firmware upgrades which enable High Performance FICON (HPF) support also contain errors which can cause Linux guests running under z/vm 6.2 with APAR VM65041 and z/vm 6.3. USERS AFFECTED: All users of z/vm 6.2 with APAR VM65041 and z/vm 6.3 running Linux guests. PROBLEM DESCRIPTION: Linux, by default, detects and uses HPF I/O whenever it is available. z/vm 6.2 with APAR VM65041 and z/vm 6.3 allow HPF I/O if enabled on the hardware. The firmware upgrade enables the HPF I/O but contains an error related to program check reporting which causes the Linux guest to fail. Related hardware alert: High Performance FICON and Traditional PAV (non Hyper PAV) can cause a loss of access to data PROBLEM RESOLUTION: There are three options to avoid the problem. 1. Upgrade to latest level of firmware (See related hardware alert link above for details). 2. Disable HPF during firmware upgrade (see related hardware alert link above). 3. Disable HPF for each Linux guest. Edit /etc/zipl.conf and add dasd_mod.dasd=nofcx to the parameters="" line. Then run the zipl command.

3 Additional updates: Dec 2013: RACFVM customer instructions Dec 2013: CA VM:Secure customer instructions November 2013 VM65248 REQUIRED TO AVOID REPEATED HTT001 ABENDS AFTER STORAGE CONTROLLER MICROCODE UPGRADE Collecting z/vm Monitor data against newer DS8000 (D/T2107) storage controllers may lead to ABENDHTT001 in HCPCM2 due to a buffer overlay when collecting performance statistics. USERS AFFECTED: All z/vm customers who are not running with VM65248 (which is on RSU 1301) and who are running with newer storage controller microcode levels. Attention RACFVM Customers: If you encounter this problem, you must take the special steps outlined below in the RACFVM Users section to prevent CP Monitor from starting when the system is IPLed. PROBLEM DESCRIPTION: z/vm repeatedly abends with ABENDHTT001 when CP MONITOR is enabled for I/O and we are trying to retrieve performance statistics from a DS8000 D/T 2107 with a newer level of microcode. The problem occurs when we try to copy the performance statistics into a buffer which is smaller than we expected. In the code we expect the data to be less than or equal to 192 bytes in length. However, prior to obtaining the performance data, we issue a Sense Subsystem Status CCW to determine the length of the performance statistics that could be returned, and with a new microcode level are told 240 bytes. We then allocate a buffer for the Perform Subsystem Function and Read Subsystem Data CCWs, and instruct (via the PDF data) the device that we only want 192 bytes of data returned. When the CCW completes, and we copy the data into the Monitor DCSS, we use the length of the 240 bytes returned from the Sense Subsystem Status CCW instead of using the buffer size (and the actual size of performance statistics) of 192 bytes of data returned. Trying to write the data into the Monitor DCSS beyond byte 192 causes the ABENDHTT001. PROBLEM CONCLUSION: To prevent the code from writing beyond the end of the buffer causing the ABENDHTT001, the code has been updated to make sure the buffer length is never greater than 192 bytes. In HCPMNA we issue the Sense Subsystem Status CCW to determine the length of the performance statistics returned. The length of of the buffer (IODCAD_PSFLEN) is then checked. If the length is greater than 192 bytes we set the length to 192, otherwise we use the length returned from the Sense CCW. This will ensure we only try to write the amount expected (192 bytes) into the Monitor DCSS preventing the abend. PROBLEM RESOLUTION: If you are encountering this problem, you may have difficulty applying the PTF for VM65248 because the z/vm system will not stay up due to the repeated abend loop. To circumvent this, do the following: 1. If you have not enabled the AUTO_Warm_IPL or AUTO_IPL feature in your SYSTEM CONFIG file to bypass the IPL "Start" prompt (where you also specify the type of start you wish to perform...warm, Force, etc.), IPL your system normally and proceed to step 2. Otherwise, you must IPL your system with the PROMPT IPL parameter on the Stand Alone Program Loader (SAPL) screen to force the "Start"

4 prompt to be issued. To bring up the SAPL screen, IPL your system with a parameter, such as a console address. Then specify PROMPT in the IPL PARAMETERS section, and proceed with the IPL. 2. Use the NOAUTOLOG option on the "Start" prompt at IPL so that the virtual machine that you are starting z/vm Monitor data collection with (for example, PERFSVM if you are using Performance Toolkit) will not automatically get logged on and lead to another HTT001 abend. You can then selectively XAUTOLOG only the userids that you need to apply the PTF for VM65248, and reipl the system. RACFVM CUSTOMERS: If you are using RACFVM on your system and you encounter this problem, you may need to take special steps to prevent CP Monitor from starting when the system is IPLed. In a z/vm system with RACFVM installed, the normal sequence at IPL time is: A) User AUTOLOG1 logs on RACFVM. B) RACFVM initializes and logs on AUTOLOG2. C) AUTOLOG2 logs on the rest of the users that are logged on at IPL time, including users that start Monitor data collection. This Monitor data collection may lead to the HTT001 abend loop. To temporarily prevent Monitor data collection on your RACFVM system, after using the NOAUTOLOG option at IPL time as described above, do the following: 1. Prevent AUTOLOG2 from logging users on: (Note: The instructions below assume that the userid called "RACFVM" is the RACFVM server that is being used. Some customers use the installation disks in production. If that is the case, then the userid associated with the RACFVM installation must be used. Following are the release-specific server names: 5.4.0: 5VMRAC : 6VMRAC : 6VMRAC30 ) From user OPERATOR, Link the RACFVM 191 and 305 disks in write mode. Access the 191 and 305 disks COPY the RACIPLXI EXEC on the RACFVM 305 disk to the RACFVM 191 disk XEDIT the RACIPLXI EXEC on the RACFVM 191 disk and comment out the logging on of AUTOLOG2, and FILE your change. 2. ReIPL your system. 3. Selectively logon or XAUTOLOG only the userids that you need to apply the PTF, and apply the PTF. 4. Erase the RACIPLXI EXEC from the RACFVM 191 disk (which means that the RACIPLXI EXEC on the RACFVM 305 disk will again be used, and the userids that normally get logged on at IPL time will be logged on normally). 5. IPL your system using your normal process. Now that you have VM65248 applied, you should no longer get the HTT001 abend loop.

5 CA VM:Secure CUSTOMERS: If you are using VM:Secure on your system and you encounter this problem, you may need to take special steps to prevent CP Monitor from starting when the system is IPLed. In a z/vm system with VM:Secure installed, the normal sequence at IPL time is: A) User AUTOLOG1 logs on VMSECURE. B) VMSECURE initializes and logs on AUTOLOG2. C) AUTOLOG2 logs on the rest of the users that are logged on at IPL time, including users that start Monitor data collection. This Monitor data collection may lead to the HTT001 abend loop. To temporarily prevent Monitor data collection on your VMSECURE system, after using the NOAUTOLOG option at IPL time as described above, do the following: 1. Manually logon to the VMSECURE server. If this is an SSI cluster, you must logon to VMSECURE on the MASTER server. Respond "NO" when prompted to initialize the VM:Secure program. 2. Comment out the PRODUCT CONFIG statement: AUTOUSER AUTOLOG2 3. IPL CMS in the server user ID to start VMSECURE 4. Selectively logon or XAUTOLOG only the userids that you need to apply the PTF, and apply the PTF 5. IPL z/vm, using the NOAUTOLOG option once again 6. Manually logon to the VMSECURE server. If this is an SSI cluster, you must logon to VMSECURE on the MASTER server. 7. Uncomment the PRODUCT CONFIG statement: AUTOUSER autolog2 8. IPL CMS in the server user ID to start VMSECURE. AUTOLOG2 should also start at this time and logon the rest of the users. Your system will now be back to normal.