On Fri, May 03, 2013 at 08:25:59PM -0600, Marcus Sorensen wrote: > > 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. There are some limited situations where it may work, > without a bitmap and some cluster aware application in control of what > blocks are written, but you can't for example mount it ext4 and write to > only one side at a time. That's why people use drbd. Sorry. I should have said what it was for. I realise that mounting a typical file system twice would be dangerous (also with drdb). The intention would have been to live migrate guest systems between C and D so the file system remains mounted (once) inside the guest system but nowhere else. Would it work in this scenario without a bitmap or would this scenario also lead to data loss? Would it make any difference if 0.9 metadata were use to create the array? Many thanks, - neil -- 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
