Re: Using the new bad-block-log in md for Linux 3.1

[Michal Soltys <soltys@ziu.info>]

W dniu 27.07.2011 06:16, NeilBrown pisze:
>
> If you create an array with this mdadm it will add a bad block log - you
> cannot turn it off (it is only 4K long so why would you want to).  Then as
> errors occur they will cause the faulty block to be added to the log rather
> than the device to be remove from the array.

I was wondering, 4KiB is "just" 512 entries assuming these are only 
64bit sector addresses - it's possible to imagine a failing drive with 
lots of not reloctable (for whatever reason) adjacent sectors, that 
could fill up the log relatively quickly (mentioned 512 entries ~ 256KiB 
worth of data on 512b drives, just a few chunks before the drive is 
kicked out). Though - how realistic such scenario is with modern drives, 
is hard for me to judge.

Still - are there any plans to make that 4KiB size not hardcoded, also 
perhaps along with customizable offset to the 1st chunk ?

Something of analogous functionality to lvm's options such as:

--metadatasize
--dataalignment
--dataalignmentoffset

(though again, hard to judge if there's any practical use for those 
aside exotic scenarios)