1391070 - Linux UUID Solutions | Linux | 64 Bit Computing

SAP Note

1391070 - Linux UUID solutions Version 33

Validity: 30.10.2013 Validity: 30.10.2013 - active

Language English (Master)

Header Data Released On

30.10.2013 17:03:50

Release Status Released for Customer Component

BC-OP-LNX Linux

Priority

Correction with high priority

Category

External error

Symptom 1. You get an error or a "SICK" message from SAP kernel (dev_disp) about a missing or inactive UUID daemon (uuidd) that points to this note, or 2. you run an application that massively uses UUIDs and you get duplicate UUIDs, or 3. you detect bad performance in an application that heavily uses UUIDs, or 4. you get an error from SAP NW RFC (dev_rfc) that points to this note or reports "ERROR pfuuid_init returns error -> UUIDs cannot be generated".

Other Terms UUID, CL_SYSTEM_UUID, libuuid, libuuid.so, Linux, SLES, RHEL, e2fsprogs, uuid daemon, uuidd, GUID, uuid-runtime, SICK, START_CALL_SICK

Reason and Prerequisites SAP ABAP and Java applications use universally unique identifiers (UUIDs) as database keys and for other purposes. On Linux those UUIDs are provided by the operating system and in case of problems with UUIDs you need to perform an upgrade on specific parts of your Linux operating system. UUIDs are generated on Linux by the "libuuid.so" shared library which comes with your Linux distribution. Older versions of "libuuid" have various bugs - e.g. duplicate UUIDs are generated and as such it is important that you install the latest available libuuid library. Especially with SAP products using 7.10 kernel or higher, UUIDs are getting more important. In this case an errorneous libuuid implementation can produce database inconsistenses that can be dangerous in productive systems. This issue arises from UUID duplicates that are possible when UUIDs are created massively in a short time period. Currently we know about such massive UUID creations in SAP banking services, in SAP SCM 7.00 EhP 1 and higher (SAP note 1640217), in SAP CRM 7.00 EhP 2, and during upgrades.

Solution The Linux operating system administrator needs to unzip and run the script that is attached to this note. This script verifies on operating system level the status of the UUID environment of your system. Please follow the instructions of the script, e.g. install or upgrade some system RPM packages. After that, please rerun the script until no further problems are reported. Consider that operating system upgrades require a stop and restart of all SAP instances (application servers) that are running on the corresponding machine. Unfortunately, in some rare cases the SICK check does not run correctly and complains "The UUID daemon (uuidd) is not active", but the check-libuuid.sh script attached to this note reports that everything is ok on OS level. We know that this can occur in SAP Solution Manager Systems. This issue is fixed as of SAP kernel 7.20 patch level 321 (7.21: PL 33, 7.38: PL 3), thus please upgrade SAP kernel accordingly. Quick Solution Overview l

l

l

l

l

Please update to latest available e2fsprogs/libuuid/uuid-runtime/uuidd e2fsprogs/libuuid/uuid-runtime/uuidd RPM package for your Linux operating system. On SLES 11 and all RHEL and OL releases make sure to afterwards activate the UUID daemon (see below). On SLES 9 and SLES 10 UUID generation is known to be slow. There is no fix planned to solve this issue. If you have performance issues, please upgrade to SLES 11. If SICK message "The UUID daemon (uuidd) is not active" appears although check-libuuid.sh reports no errors, please upgrade SAP kernel 7.20 to patch level 321 or higher (7.21: PL 33, 7.38: PL 3). If "Error 20012 in Linux UUID check" appears, then this is no problem of the UUID environment. Error 20012 indicates an out-of-memory problem on the Linux server. Please check its memory

configuration. Detailled UUID Implementation Overview

Here is a summary about the current status of UUID implementations as found on installed SLES (SuSE Linux Enterprise Server), RHEL (Red Hat Enterprise Linux), and OL (Oracle Linux) releases. 1. Old errorneous implementation (may generate UUID duplicates) ¡

SLES 9 up to SP3, e2fsprogs up to version e2fsprogs-1.38-4.17

¡

SLES 10, e2fsprogs up to version e2fsprogs-1.38-25.8

¡

RHEL 4 up to RHEL 4.7, up to e2fsprogs-1.35-12.23.el4

¡

RHEL 5 up to RHEL 5.2, up to e2fsprogs-1.39-14.el5

2. Errorneous SuSE implementation: can cause system failures due to shared-memory limitations. This implementation should never be used! See SAP note 1065860. ¡

SLES 9

(SP3): e2fsprogs-1.38-4.18 e2fsprogs -1.38-4.18 to e2fsprogs-1.38-4.20

¡

SLES 10 (SP1): e2fsprogs-1.38-25.9 to e2fsprogs-1.38-25.23

3. SuSE implementation via shared memory: known to be slow, does not work correctly (produces duplicates) on virtualized systems with VMware 3.x, but works fine on native systems and virtualized systems with VMware 4.0 or other virtualization technologies. ¡

SLES 9: since SP4, since e2fsprogs-1.38-4.21

¡

SLES 10: since SP2, since e2fsprogs-1.38-25.24

4. Second fixed SuSE implementation via shared memory. This solution works correctly also on virtualized systems under VMware 3.x, but is as slow as the previous implementation. ¡

¡

SLES 9: This fix is not available. The support of SLES 9 ended August 2011 - you should prefer an upgrade of the system to SLES 10 or better to SLES 11. SLES 10: since e2fsprogs-1.38-25.36.1

5. Almost functional correct upstream solution via uuidd daemon. This solution works correctly in most cases, but if the uuidd has to manage masses of UUIDs immediately after (re-) startup of the uuid daemon, it could produce duplicates. This could happen if the uuid daemon runs on demand (i.e. the uuidd daemon stops itself after a certain timeout if no time-based UUIDs were generated - this is the default). Please note that the uuid daemon needs to be activated (see following section "UUID Daemon (uuidd) Activation"). ¡

¡

¡

SLES 11: packages libuuid1 + uuid-runtime RHEL 4: packages e2fsprogs + uuidd, since RHEL 4.8, since e2fsprogs-1.35-12.24.el4 e2fsprogs-1.35-12.24.el4 and uuidd-1.35-12.24.el4 RHEL 5: packages e2fsprogs + uuidd, since RHEL 5.3, since e2fsprogs-1.39-15.el5 and uuidd1.39-15.el5

¡

OL 5: packages e2fsprogs + uuidd, since OL 5.5 (first OL release that is supported by SAP)

¡

RHEL 6, OL 6: packages libuuid + uuidd

6. Functional correct upstream solution via uuidd daemon. This fixes also the startup issue mentioned in the previous item. Please note that the uuid daemon needs to be activated (refer following section "UUID Daemon (uuidd) Activation"). ¡

¡

¡

¡

SLES 11: packages libuuid1 + uuid-runtime, since libuuid1-2.16-6.11.1 libuuid1-2.16-6.11.1 and uuid-runtime-2.166.11.1, the fix will be included in SLES 11 SP2. RHEL 4: This fix is not available. Please note that RHEL 4 runs out of support in 2012. But it is possible to avoid startup issues if the uuid daemon runs permanently. This is the case if the uuid daemon is started as system service ('chkconfig uuidd ...', 'service uuidd ...'). To check whether the uuid daemon is running permanently or on demand, you may run the script that is attached to this note. Do not use the misleading 'status' option of 'chkconfig' or 'service'. RHEL 5, OL 5: packages e2fsprogs + uuidd, since RHEL 5.7, since e2fsprogs-1.39-33.el5 e2fsprogs-1.39-33.el5 and uuidd-1.39-33.el5 RHEL 6, OL 6: packages libuuid + uuidd, since RHEL 6.1, since libuuid-2.17.2-12.el6 and uuidd-2.17.2-12.el6

UUID Daemon (uuidd) Activation

The UUID daemon is a helper tool which syncronizes UUID generation across all processes running on the Linux system. It usually runs in on-demand mode, i.e. it runs as long as time-based UUIDs are requested. The daemon solution (mentioned in the last two items in the list above) needs to be activated. In standard Linux installations the uuid daemon is usually not active! Without uuidd activation the libuuid still uses the standard algorithm that may produce duplicates!

l

l

l

l

l

SLES 9 and SLES 10: No UUID daemon available, just use a recent version of e2fsprogs. SLES 11: In order to activate the uuidd solution, you need to install the uuid-runtime RPM package and additionally you need to follow the instructions in /usr/share/doc/pack /usr/share/doc/packages/uuidages/uuidruntime/README.SUSE.uuidd. SLES 11 SP1 or higher: You simply need to install the sapconf RPM package (this is necessary for SAP installations anyhow). The package sapconf incorporates the dependencies to uuid-runtime and performs the README.SUSE.uuidd instructions above automatically. The sapconf package is already installed if you install SLES 11 SP1 or higher as described in note 1310037. RHEL 4: In order to activate the UUID daemon you need to install the uuidd RPM package. Additionally, it is required to run the UUID daemon permanently with command 'service uuidd start', respective 'chkconfig uuidd on' (as root). RHEL 5, RHEL 6, OL 5, OL 6: In order to activate the UUID daemon you need to install the uuidd RPM package. Additionally, it is required to run the UUID daemon permanently as system service with 'service uuidd start' and 'chkconfig uuidd on' (as root user). (Alternatively, for starting the UUID daemon in the on-demand mode, you need run the command 'chmod 6755 /usr/sbin/uuidd' as root user.)

Validity Software Component From Rel. To Rel. KRNL32NUC 7.10 7.20

KRNL32UC

KRNL64NUC

KRNL64UC

KERNEL

7.20EXT 7.21

7.20EXT 7.21

7.21EXT

7.21EXT

7.10

7.20

7.20EXT

7.20EXT

7.21 7.21EXT

7.21 7.21EXT

7.10

7.20

7.20EXT

7.20EXT

7.21

7.21

7.21EXT

7.21EXT

7.38 7.40

7.38 7.40

7.10

7.20

7.2L

7.2L

7.20EXT

7.20EXT

8.00 8.02

8.00 8.02

8.03

8.03

8.04

8.04

7.21

7.21

7.21EXT

7.21EXT

7.38 7.40

7.38 7.40

7.10

7.11

7.20

7.21

7.2L

7.2L

8.00

8.04

7.38

7.38

7.40

7.40

And Subsequent

Support Packages & Patches Support Package Patches

Software Component SAP KERNEL 7.10 32-BIT

Support Package Patch Level SP203 000203 SP261

000261

SAP KERNEL 7.10 32-BIT UNICODE SP203

000203

SP261 SP203

000261 000203

SP261

000261

SAP KERNEL 7.10 64-BIT UNICODE SP203

000203

SAP KERNEL 7.10 64-BIT