ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks

Damien Fleuriot ml at my.gd
Wed Jan 5 09:02:04 UTC 2011

Hi again List,

I'm not so sure about using raidz2 anymore, I'm concerned for the performance.

Basically I have 9x 1.5T sata drives.

raidz2 and 2x raidz1 will provide the same capacity.

Are there any cons against using 2x raidz1 instead of 1x raidz2 ?

I plan on using a SSD drive for the OS, 40-64gb, with 15 for the system itself and some spare.

Is it worth using the free space for cache ? ZIL ? both ?

@jean-yves : didn't you experience problems recently when using both ?

Fleuriot Damien

On 3 Jan 2011, at 16:08, Damien Fleuriot <ml at my.gd> wrote:

> On 1/3/11 2:17 PM, Ivan Voras wrote:
>> On 12/30/10 12:40, Damien Fleuriot wrote:
>>> I am concerned that in the event a drive fails, I won't be able to
>>> repair the disks in time before another actually fails.
>> An old trick to avoid that is to buy drives from different series or
>> manufacturers (the theory is that identical drives tend to fail at the
>> same time), but this may not be applicable if you have 5 drives in a
>> volume :) Still, you can try playing with RAIDZ levels and probabilities.
> That's sound advice, although one also hears that they should get
> devices from the same vendor for maximum compatibility -.-
> Ah well, next time ;)
> A piece of advice I shall heed though is using 1% less capacity than
> what the disks really provide, in case one day I have to swap a drive
> and its replacement is a few kbytes smaller (thus preventing a rebuild).

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