Re: ASM vs. dNFS?
From: Mladen Gogala <gogala.mladen_at_gmail.com>
Date: Wed, 24 Feb 2016 00:45:35 -0500
Message-ID: <56CD437F.6000407_at_gmail.com>
On 02/23/2016 03:01 PM, Seth Miller wrote:
>
> It is unclear to me why storage snapshots for ASM disk groups required
> you to use RDMs. Could you not snap multiple VMDKs at the same time?
>
Because it's impossible to determine the LUN from within the guest OS, if the VMDK layer is between the guest and the LUN. Snapshot scripts first have to tell storage which LUN to snap. If the underlying disk is VMDK, that is impossible, since VMWare virtualizes disk and hides the hardware from the OS.
Date: Wed, 24 Feb 2016 00:45:35 -0500
Message-ID: <56CD437F.6000407_at_gmail.com>
On 02/23/2016 03:01 PM, Seth Miller wrote:
>
> It is unclear to me why storage snapshots for ASM disk groups required
> you to use RDMs. Could you not snap multiple VMDKs at the same time?
>
Because it's impossible to determine the LUN from within the guest OS, if the VMDK layer is between the guest and the LUN. Snapshot scripts first have to tell storage which LUN to snap. If the underlying disk is VMDK, that is impossible, since VMWare virtualizes disk and hides the hardware from the OS.
-- Mladen Gogala Oracle DBA http://mgogala.freehostia.com -- http://www.freelists.org/webpage/oracle-lReceived on Wed Feb 24 2016 - 06:45:35 CET