Symptom
You are using a SAP HANA database revision on an SPS below 10 and
deployed the /tmp directory not on a local storage or ram disk, and you
have seen performance fluctuations during query executions.
In the thread overview in HANA Studio you see many threads in mutex locks with callstacks as below:
1 : syscall+0x15 (libc.so.6)
2 : Synchronization::Mutex::lock(Execution::Context&)+0x1a8 at LinuxFutexOps.hpp:53 (libhdbbasis.so)
3 : TrexIpc::NameserverLock::acquireRead()+0x180 at TrexIpc.cpp:734 (libhdbbasement.so)
4 : NameServer::FTreeContainer::getValue(ltt_adp::basic_string<char, ltt::char_traits<char>, ltt::integral_constant<bool, true> > const&, ltt::basic_string<char, ltt::char_traits<char> >&)+0x31 at RWLock.h:46 (libhdbns.so)
5 : NameServer::NameServerProxy::getValue(ltt_adp::basic_string<char,
Since SPS09 revision 91 HANA is checking during the startup the filesystem of /tmp and report an unsupported filesystem in the daemon trace with an error entry like: "...lock file <LockName> is on unsupported <filesystem type> filesystem, see SAP note 2100296" .
In the thread overview in HANA Studio you see many threads in mutex locks with callstacks as below:
1 : syscall+0x15 (libc.so.6)
2 : Synchronization::Mutex::lock(Execution::Context&)+0x1a8 at LinuxFutexOps.hpp:53 (libhdbbasis.so)
3 : TrexIpc::NameserverLock::acquireRead()+0x180 at TrexIpc.cpp:734 (libhdbbasement.so)
4 : NameServer::FTreeContainer::getValue(ltt_adp::basic_string<char, ltt::char_traits<char>, ltt::integral_constant<bool, true> > const&, ltt::basic_string<char, ltt::char_traits<char> >&)+0x31 at RWLock.h:46 (libhdbns.so)
5 : NameServer::NameServerProxy::getValue(ltt_adp::basic_string<char,
Since SPS09 revision 91 HANA is checking during the startup the filesystem of /tmp and report an unsupported filesystem in the daemon trace with an error entry like: "...lock file <LockName> is on unsupported <filesystem type> filesystem, see SAP note 2100296" .
Other Terms
performance, /tmp, lock file, interprocess, shared memory, SAP HANA
Reason and Prerequisites
You are running a SAP HANA revision on an SPS below 10 on a Linux
operating system. The /tmp directory of the operating system on which
the SAP HANA database is running is not on a local storage or disk. A
running SAP HANA database will store a read/write lock file for shared
memory accesses in the /tmp directory. This lock file is used for
interprocess communication of the SAP HANA database and its write
performance has an impact on the overall database performance.
Solution
The /tmp directory must be placed on a local disk to ensure maximum performance of the SAP HANA database.
Header Data
| Released On | 04.11.2015 16:28:53 |
| Release Status | Released for Customer |
| Component | HAN-DB SAP HANA Database |
| Priority | Recommendations / Additional Info |
| Category | Installation information |
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