Re: Raid1 replaced with raid10?

[Peter Rabbitson <rabbit@rabbit.us>]

Neil Brown wrote:
> On Friday May 4, davidsen@tmr.com wrote:
>> Peter Rabbitson wrote:
>>> Hi,
>>>
>>> I asked this question back in march but received no answers, so here it
>>> goes again. Is it safe to replace raid1 with raid10 where the amount of
>>> disks is equal to the amount of far/near/offset copies? I understand it
>>> has the downside of not being a bit-by-bit mirror of a plain filesystem.
>>> Are there any other caveats?
>>>   
> 
> To answer the original question, I assume you mean "replace" as in
> "backup, create new array, then restore".
> You will get different performance characteristics.  Whether they
> better suit your needs or not will depend largely on your needs.

Hi Neil,
Yes I meant take an existing 2 drive raid1 array (non bootable data) and
put a raid10 array in its place. All my testing indicates that I get the
same write performance but nearly double the read speed (due to
interleaving I guess). It seemed to good to be true, thus I am asking
the question. Could you elaborate on your last sentence? Are there
downsides I could not think of? Thank you!

Peter