On Wed, 9 Mar 2022 11:04:03 -0500 David T-G <davidtg-robot@xxxxxxxxxxxxxxx> wrote: > Is it OK to mirror a partition and an entire device? Yes it is OK. > jpo:~ # parted /dev/sdb unit MiB print > Model: ATA ST31000524AS (scsi) > Disk /dev/sdb: 953870MiB > Sector size (logical/physical): 512B/512B > Partition Table: gpt > Disk Flags: > > Number Start End Size File system Name Flags > 1 1.00MiB 858307MiB 858306MiB xfs pri > 4 950055MiB 953869MiB 3814MiB pri > Here it seems weird that your 1TB drive has a 858GB partition, then a hole of free space about 92 GB in size, and only then another partition of 4 GB. In preparation for that partition to become a RAID member (instead of xfs data directly), you could resize it to match the 944082MiB size of md0. > with existing data (and having to fudge around, not surprisingly, the > striping metadata overhead), and so I've been playing > > jpo:~ # parted /dev/md0 unit MiB print > Model: Linux Software RAID Array (md) > Disk /dev/md0: 944082MiB > Sector size (logical/physical): 512B/512B > Partition Table: gpt > Disk Flags: > > Number Start End Size File system Name Flags > 1 1.00MiB 934641MiB 934640MiB 500Graid0md raid > 4 934641MiB 944081MiB 9440MiB pri msftdata > > with how to slice up the stripe device to size it to match the existing > sdb1 partition with the mirroring metadata overhead, when I wondered ... > do I care? I don't need the s4 slice on this virtual device; that's just > leftover space. I hate to think of it going to waste, but it's really > trivial in the grand scheme of things. Soooooo ... if it's just as happy > to mirror against a whole device as it is a slice of one, then maybe I > can skip ahead. It is definitely an overkill to partition the md0 device. Better to just use it entirely. If you fix up the partition size on sdb as mentioned above, there will not be any wasted space on md0. -- With respect, Roman
