Re: ASM question
- From: "Alex Gorbachev" <gorbyx@xxxxxxxxx>
- To: "Greg Rahn" <greg@xxxxxxxxxxxxxxxxxx>
- Date: Sun, 25 Feb 2007 17:56:00 -0500
Greg,
See few notes inline.
On 2/24/07, Greg Rahn <greg@xxxxxxxxxxxxxxxxxx> wrote:
To quote the documentation:
http://download-east.oracle.com/docs/cd/B19306_01/server.102/b14231/storeman.htm
for normal redundancy:
FREE_MB - REQUIRED_MIRROR_FREE_MB = 2 * USABLE_FILE_MB
or
(FREE_MB - REQUIRED_MIRROR_FREE_MB)/2 = USABLE_FILE_MB
Using the below example's numbers:
(20374 - 5120)/2 = 7627
Oracle documentation you quoted only confirms that those calculation
are valid when every disk is in each own failure group (default):
"The following query shows capacity metrics for a normal redundancy
disk group that consists of six 1 GB (1024 MB) disks, each in its own
failure group."
The case with many disks in two failure groups is a special case and
this formula is incorrect.
At this point I'm going to recommend reading the Metalink note 395712.1
because there is a similar example worked out as well as some other
useful questions & answers.
Looks like ML Note 395712.1 is non-public.
I would also agree that external mirroring may be more simple. There
isn't even a need for Veritas as a lvm. Just RAID it on the DMX3000.
If you are mirroring over different storage boxes than host based
mirroring is the way to go. Perhaps, some storage vendors provide
cross boxes mirroring.
--
Best regards,
Alex Gorbachev
http://www.oracloid.com
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