On Fri, Aug 28, 2015 at 4:27 PM, Song Liu <songliubraving@xxxxxx> wrote: > Specify the write journal device with --write-journal DEVICE > > ./mdadm --create -f /dev/md0 --assume-clean -c 32 --raid-devices=4 --level=5 /dev/sd[c-f] --write-journal /dev/sdb1 > mdadm: Defaulting to version 1.2 metadata > mdadm: array /dev/md0 started. > > Only one journal device is allowed. If multiple --write-journal > are given, mdadm will use the first and ignore others > > ./mdadm --create -f /dev/md0 --assume-clean -c 32 --raid-devices=4 --level=5 /dev/sd[c-f] --write-journal /dev/sdb1 --write-journal /dev/sdx > mdadm: Please specify only one journal device for the array. > mdadm: Ignoring --write-journal /dev/sdx... > mdadm: Defaulting to version 1.2 metadata > mdadm: array /dev/md0 started. Hmm, perhaps this should instead follow the same command line mechanics as "--write-mostly" whereby all the devices listed after that flag take on that role. Also, if we anticipate more roles I wonder if the option should be "--role=" that assigns the given role to the device(s) that follow. Thoughts? I'm looking at this from the perspective of reviving the SRT patches [1] where a role for a read/write cache device is needed. Where a read/write-cache is different than a journal. [1]: https://lwn.net/Articles/596614/ -- 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
