On 06.05.2013 08:32, NeilBrown wrote: > On Sat, 4 May 2013 14:01:46 +1200 Neil Matai <neil@xxxxxxxxxxxxx> > wrote: > >> Hi all, >> >> Is it dangerous have an array assembled on two hosts at the same >> time? Say I have servers A and B exporting devices a and b via >> ATA over Ethernet or similar to hosts C and D. If a and b are >> components of an array then both C and D automatically assemble >> the array as soon as the components a and b are exported but is >> this safe (on the proviso that only one of C or D is ever writing >> to the array at any time and that there is no write-behind >> caching above the array device)? >> > > Yes, it is dangerous. Both hosts will try to update the metadata > and will trip over each other. This is why we've implemented automatic super block + bitmap reload upon first IO. Before, the MD device acts as a read-only device with read-only super block. This is rather complex to make it safe. This is also difficult to merge with mainline behavior. Get yourself a kernel developer. ;-) Cheers, Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
