SAP Knowledge Base Article - Preview

2478246 - Performance of tempdb clearing on startup - SAP ASE

Symptom

  • Slow tempdb clearing on startup
  • Variation in peformance of tempdb availability on startup
  • Long time to online tempdb
  • ASE log shows (big) variation in time to online temdb : 

13 seconds :
14:07:23.59 server  Clearing temp db 
14:07:25.50 server  Processed 1640 allocation unit(s) out of 16392 units (allocation page 419584). 10% completed.
...
14:07:35.51 server  Processed 16392 allocation unit(s) out of 16392 units (allocation page 4196096). 100% completed.
14:07:36.50 server  Database 'tempdb' is now online.

~1 minute :
11:37:47.87 server  Clearing temp db
11:37:55.63 server  Processed 1640 allocation unit(s) out of 16392 units (allocation page 419584). 10% completed
....
11:38:51.54 server  Processed 16392 allocation unit(s) out of 16392 units (allocation page 4196096). 100% completed.
11:38:52.73 server  Database 'tempdb' is now online.

 ~1 hour :
10:18:27.54 server  Clearing temp db 
10:25:03.34 server  Processed 1640 allocation unit(s) out of 16392 units (allocation page 419584). 10% completed.
...
10:44:16.11 server  Processed 6557 allocation unit(s) out of 16392 units (allocation page 1678336). 40% completed.
...
11:22:35.51 server  Processed 16392 allocation unit(s) out of 16392 units (allocation page 4196096). 100% completed.
11:22:36.50 server  Database 'tempdb' is now online.

  • Using asynchronous IO on file system devices.
  • This is liable to manifest as severe performance degradation on single CPU machines and significant performance degradation on multi CPU machines under load.

Read more...

Environment

  • SAP Adaptive Server Enterprise (ASE) all versions.
  • OS Sun Solaris 10

Product

SAP Adaptive Server Enterprise all versions ; Sybase Adaptive Server Enterprise all versions

Keywords

"Clearing temporary database 'tempdb'" , "Clearing temp db" , tempdb startup performance , Processed allocation unit(s) ,  Processed , allocation unit(s) , slow tempdb start , tempdb slow start , tempdb slow startup , sybase, ase , KBA , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Problem

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