Thin Provisioning and Operationalizing ASRU?

From: Adam Musch <ahmusch@xxxxxxxxx>
To: Oracle Freelist <oracle-l@xxxxxxxxxxxxx>
Date: Fri, 27 Sep 2013 11:33:11 -0500

My company is evaluating a thin provisioned storage array, and one of the
issues we ran into is the need to run the ASM Reclamation Utility (asru) as
we purge data, as we've isolated isolate date-ranged partitions to specific
tablespaces to help optimize backups, as old tablespaces can be put into
read-only mode.
Is anyone out there using ASRU on a day-to-day or month-to-month basis, and
if so, how have you operationalized it, or have you?

We're using ASM with RAC; if we were using a file system, the thin
provisioning reclamation against the array would happen automagically.

My concerns with the utility are multiple:

1.  How safe is it to run this utility while the database is open and
running?  Do you do so as part of your normal purge operations?

2.  Is free space internal to an ASM disk reclaimed?  I can see from the
trace files that it will zerofill space after it resizes the ASM disk down,
but does it reorganize/compact the in-use stripes of the ASM disk prior to
doing so?  If the utility works functionally like resizing a datafile -
i.e., only to the HWM - how much use is it?

3.  How does one prevent, absent training and education, from preventing a
manual or automatic rebalance or other administrative ASM disk operation
from conflicting with ASRU?

Thanks very much for any input or other experiences you may have had with
ASRU and thin provisioning with ASM disks, regardless of storage vendor.


-- 
Adam Musch
ahmusch@xxxxxxxxx


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Thin Provisioning and Operationalizing ASRU?

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