Re: limits on raid

2007-06-17 Thread Andi Kleen
Neil Brown [EMAIL PROTECTED] writes: Having the filesystem duplicate data, store checksums, and be able to find a different copy if the first one it chose was bad is very sensible and cannot be done by just putting the filesystem on RAID. Apropos checksums: since RAID5 copies/xors anyways it

Re: limits on raid

2007-06-17 Thread Wakko Warner
dean gaudet wrote: On Sat, 16 Jun 2007, Wakko Warner wrote: When I've had an unclean shutdown on one of my systems (10x 50gb raid5) it's always slowed the system down when booting up. Quite significantly I must say. I wait until I can login and change the rebuild max speed to slow it

Re: limits on raid

2007-06-17 Thread Bill Davidsen
Neil Brown wrote: On Thursday June 14, [EMAIL PROTECTED] wrote: On Fri, 15 Jun 2007, Neil Brown wrote: On Thursday June 14, [EMAIL PROTECTED] wrote: what is the limit for the number of devices that can be in a single array? I'm trying to build a 45x750G array and want to

Re: limits on raid

2007-06-17 Thread Wakko Warner
dean gaudet wrote: On Sun, 17 Jun 2007, Wakko Warner wrote: i use an external write-intent bitmap on a raid1 to avoid this... you could use internal bitmap but that slows down i/o too much for my tastes. i also use an external xfs journal for the same reason. 2 disk raid1 for

Re: limits on raid

2007-06-17 Thread David Chinner
On Sat, Jun 16, 2007 at 07:59:29AM +1000, Neil Brown wrote: Combining these thoughts, it would make a lot of sense for the filesystem to be able to say to the block device That blocks looks wrong - can you find me another copy to try?. That is an example of the sort of closer integration