Re: write barriers on raid0 and raid10

[Bill Davidsen <davidsen@tmr.com>]

Iordan Iordanov wrote:
> Hi,
>
> We are designing a rather involved file server with an ext3 formatted 
> stripe (raid0) sitting on top of raid10 devices. Each raid10 device 
> sits on top of 3 iscsi targets, and has layout n3 (so it is 
> effectively a 3 way mirror). We chose raid10 over raid1 due to an 
> apparent read performance benefit of raid10.
>
> We are trying to decide whether to upgrade to a kernel newer than 
> 2.6.34, where write barriers are ostensibly supported by all possible 
> raid types, because we are worried about ext3 corruption with no write 
> barrier support.
>
> However, we are also worried about whether write barriers really "make 
> sense" in a multi-disk environment and are wondering whether they will 
> actually make a difference in our setup. For argument's sake, let's 
> assume that our drives honor write cache flushes.
>
> Can somebody shed some light on how write barriers are implemented in 
> raid0 and raid10? Also, any critical comments on the validity of our 
> setup and/or assumptions is also welcome.
>
I'm sorry not to see an answer here, I'm interested as well.

-- 
Bill Davidsen <davidsen@tmr.com>
  "We can't solve today's problems by using the same thinking we
   used in creating them." - Einstein