Re: ASM disk path in exadata
- From: Frits Hoogland <frits.hoogland@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Tue, 21 Feb 2012 13:07:24 +0100
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There is no udev/path translation on the database/computing layer in =
exadata.
During startup, ASM first needs to find the disks. It does that by =
picking up the cellserver information (addresses) in =
/etc/oracle/cell/network-config/cellip.ora
Because the discovery string is set to "o/*/*", it picks up all =
griddisks available on the cellservers defined in cellip.ora
Because of the entirely different path, ASM knows it needs to =
communicate over the network to get to the griddisks, instead of using a =
locally attached disk. This combination is RDS (infiniband) on Exadata, =
but can be UDP (ethernet).
In fact, the discovery can manually be done by using kfod:
kfod asm_diskstring=3D"o/*/*", disks=3Dall
this is what the asmca uses behind the GUI to discover disks, also on =
normal platforms.
When specifying the o/*/* diskstring, kfod too reads =
/etc/oracle/cell/network-config/cellip.ora to know where to look.
Frits Hoogland
http://fritshoogland.wordpress.com
mailto:frits.hoogland@xxxxxxxxx
cell: +31 6 53569942
On Feb 21, 2012, at 10:32 AM, gaurav mehta wrote:
> I have been trying to figure out how exadata griddisks are presented =
as candidate asm disks. We know that the disk discovery path for asm =
instances using exadata is "o/<cell_ip_address>*/<griddisk_name>*". I =
was wondering what actual path / udev in the operating system on the db =
machine does this translate to ?. =20
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