On Sat, Dec 06, 2014 at 02:02:50PM +1100, Brett Pemberton wrote:
> On Sat, Dec 6, 2014 at 9:16 AM, Tim Hamilton <[email protected]> wrote:
> > I'm in need of a PCIe SATA controller that works well under linux
> > and supports BTRFS / ZFS raid arrays to be used in a home NAS I'm
> > building and am no sure what I'm looking for.
> >
> > My current need is only for a single additional SATA port but my
> > preference is for a card that will support future expansion
>
> Keep in mind, with ZFS for example, you can't do like mdadm, and
> just add a drive to a RAID5/6 array and reshape, growing to use more
> devices.
>
> Your best bet is to start off with the maximum number of drives you
> plan to use, and upgrade capacities, instead of adding more devices.

remember, though, that you can always add another vdev to a ZFS pool.

you can't reshape a zpool, or remove a vdev from it (and zfs doesn't
have a 'rebalance' feature like btrfs) but adding a vdev works.

e.g. if you have a zpool consisting of one three drive raidz vdev, you
could later add another vdev of any kind (e.g. another raidz, a 2-drive
mirror, etc. a vdev can even be a single disk but you get no redundancy
from that - similar to raid0).

a zpool is made up of one or more vdevs, which are each made up of one
or more drives.

you can also replace the drives in any vdev with larger capacity
drives....when all drives in that vdev are replaced, the extra capacity
is available for storage.

craig

ps: performance on a zfs pool is notably improved (especially for random
writes) if you have a small (4 or 8GB is plenty) SSD partition as a zfs
log device.

-- 
craig sanders <[email protected]>
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