Some time ago i´ve seen a discussion on OTN about ASM and thin provisioned volumes.
Hi there, sorry for the x-post from database-general but it was suggested that I do so.
Anyhow, we've got 11g (11.1.0.7 with the 6851110 ASM patch recently applied) running on
OEL 5 x86_64, with ASM connected to a raw, thin-provisioned ISCSI volume partitioned for
+DATA and +FRA, and in every case where we do so, the SAN device reports within a few
weeks that the whole volume has been allocated even though the DB (configured with
autoextend on) is only holding about one tenth of the amount of available space on the
device. What this means in systems terms is that somehow ASM is marking writes to nearly
every block on the drive if only momentarily.
In the original thread, there was speculation that a process of indexing AUs has led to
the dirtying of the whole volume, but this would make more sense if the whole disk had been
allocated immediately rather than over the course of a few weeks. My question is: what else
could account for this behavior, and what steps can I take to help ensure that ASM behaves
correctly in a thin-provisioned volume? (by "correctly" I mean writes contiguous blocks of
data and doesn't dirty the whole thing)
Yesterday i had some spare time available to dig a little bit deeper. I had a Windows-based system at hand and performed some smaller tests.
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