RE: ASM is single point of failure ?
- From: "Kevin Closson" <kevinc@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Sun, 7 May 2006 21:00:37 -0700
>In a RAC env, you will have an ASM instance on each node, so there is
no SPOF (beside
>your disks, but they are usually mirrored, so the risk is lessened).
If you lose an ASM instance, all the database
instances on that node are worthless. You must
have a local ASM instance. This post makes it
sound as though somehow any surviving ASM instance
is sufficient and that is not the case.
This debate over ASM will get old soon. If you have no
other way to get RAID 1 and 0, then use ASM.
On the other hand, Oracle has certifaction programs
for such functionality as 3rd Party CFS (which generally
have volume managers underlying). To see which ones
are available on Linux, go here:
http://www.oracle.com/technology/products/database/clustering/certify/te
ch_linux_x86.html
To see what the program is for this testing go here:
http://www.oracle.com/technology/software/oce/oce_fact_sheet.htm
If you ignore these certification programs and the technology
listed there, then ASM is for you. If you want to use Oracle datafiles
the way it has been done for 30 years (thus not "trying" new stuff),
than go with a certified CFS.
In the end, however, stating on this list that you have a
couple of RAC servers (with or without ASM) that are nice and
stable is only a case in point and doesn't mean the mix is
stable. It just means it has worked in your environment.
Not everyone on this list leaps to experiment with their
production data, particular on any technology that fundamentally
changes how Oracle has done storage for 30 years.
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