Re: ASM LUN sizes and number of disks

From: jason arneil <>
Date: Mon, 10 Nov 2008 09:14:43 +0000
Message-ID: <>


2008/11/8 Finn Jorgensen <>

> Because of the way ASM distributes data evenly across all disks in a
> diskgroup, adding 200GB disks to an existing diskgroup comprising of 50GB
> disks means you will never be able to use more than 50GB of those 200GB
> disks.

I think it's worth emphasising that ASM attempts to fill each device in a diskgroup up to the same CAPACITY. So a device that is x 4 the size of another device within the same diskgroup should in theory receive 4 times the number of extents meaning it would be able to be filled beyond the 50GB.

As long as you rebalance when adding the device so that the 50GB are not full already!

> You will have to add those disks to a separate diskgroup and then start
> moving data over, which means downtime.
> Finn



Received on Mon Nov 10 2008 - 03:14:43 CST

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