Oracle Scratchpad

August 14, 2009

Tera-bug

Filed under: Infrastructure,Troubleshooting — Jonathan Lewis @ 12:26 pm BST Aug 14,2009

I came across an interesting Oracle error recently: “ORA-15099: disk {name} is larger than maximum size of 2097152 MBs”, which you can find on Metalink under bug 7243305.

The status of this bug is: “Closed, Not a Bug” – but the description points you to bug 6453944 (present in 10.2.0.3, fixed in 11.2) for which the only visible text is:

RELEASE NOTES: ORA-15196(ASM block corruption) occured, if larger than 2TB disk was part of a diskgroup
REDISCOVERY INFORMATION: If you added larger than 2TB size disk to a diskgroup and saw ORA-15196, then you hit this issue.
WORKAROUND: Not to add larger than 2 TB size disk to a diskgroup

The text for bug note 6453944.8 tells you that the patch (to stop you creating diskgroups with oversize LUNs) is in the 10.2.0.4 and 11.1.0.7 patch sets – but the patch only stops you adding new oversize LUNs, it doesn’t help if you’re already using them. So if you’re running a very large system on ASM, you might want to check the sizes of your ASM volumes and take some remedial action if you’ve already got LUNs larger than 2TB.

There are no clear indications of what can go wrong with ASM LUNs larger than 2TB – but one example is wrapping: when Oracle gets to the end of 2TB, it may wrap back to the start of the LUN and overwrite the ASM metadata. When you’re running that big a system and need to do a full ASM disk group restore that’s a serious problem.

 

Useful related notes:

Metalink Doc ID: 370921.1: ASM – Scalability and Limits
Metalink Doc ID: 736891.1: ORA-15196 WITH ASM DISKS LARGER THAN 2TB

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