>>>>> "Mateusz" == Mateusz Korniak <mateusz-lists@xxxxxxxxxxxxxx> writes: Mateusz> On Thursday 27 of April 2017 10:25:35 John Stoffel wrote: Ron> issued these commands one after the other: >> Ron> # mdadm --manage -a /dev/mdo /dev/sdb1 Ron> # mdadm --manage -a /dev/md1 /dev/sdb2 Ron> # mdadm --manage -a /dev/md2 /dev/sdb3 Ron> # mdadm --manage -a /dev/md3 /dev/sdb5 Ron> # mdadm --manage -a /dev/md4 /dev/sdb6 Ron> # mdadm --manage -a /dev/md5 /dev/sdb7 Ron> # mdadm --manage -a /dev/md6 /dev/sdb8 Ron> # mdadm --manage -a /dev/md7 /dev/sdb9 >> >> Ugh! You're setting yourself up for a true seek storm here, and way >> too much pain down the road, IMHO. Just mirror the entire disk and >> put LVM volumes on top. Mateusz> Why having several md devices leads to "seek storm"? It might if MD isn't being smart enough, which might happen. Mateusz> They will be synced one by one, just like one big md device. No, big MD devices are sync'd in parallel assuming MD thinks they're on seperate devices. Now in this case I admit I might have jumped the gun, but I'm mostly commenting on the use of multiple MD RAID setups on a single pair of disks. It's inefficient. It's a pain to manage. You lose flexibility to resize. Just create a single MD device across the entire disk (or possibly two if you want to boot off one mirrored pair) and then use LVM on top to carve out storage. More flexible. John -- 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
