On 2014-09-10 16:59, Trevor Cordes wrote:
Outside of the enterprise space, I can see lots of scenarios where you want to add a less-than-double amount of disks to an existing array. Especially for home use, where you only want to do the big $1500 outlay on disks every 3-6 years (generally when capacities per $ have doubled).
Yup. Although even in the home-user situation, there are a lot of 4-bay enclosures where adding one more disk can't happen anyway.
If you find yourself in the "shoot, we should have bought 1 more disk" after your array is full, then having no option but buying another X drives when your budget is spent kind of sucks. The ability to solve a full-array problem by spending just $150 on one disk at any time is very attractive.
I definitely agree with you on that point.
ZFS has three critical flaws from my perspective: 1) needs way too much RAM for deduplication 2) license (although FreeBSD and Linux both work around this quite well) 3) inability to alter raid volume topology after creation
I have a funny feeling that md and the FS's on top of it will slowly add many ZFS features to be almost as rich as ZFS.
Well... yes and no. The development is mostly happening on btrfs, which is intended to be a head-to-head competitor to ZFS, including the ability to integrate the md layer into the filesystem layer directly. (This allows for much more intelligent - i.e. faster - failed-drive rebuilds, if the array isn't close to being full.)
DragonFlyBSD has also done some amazing work on the HammerFS filesystem, which was designed as a "better-than-ZFS" option from the outset. It's not yet ported to any other OS (AFAIK) and lacks true built-in RAID functions, but in other ways is a very exciting filesystem.
I guess you could say that ZFS is already a "legacy" filesystem, in the sense that it's well-established, widely-adopted, and it already has competitors nipping at its heels. XFS is in pretty much the same boat, but is a little older, and relies on a RAID block-layer device like most filesystems. Not to say these aren't valid choices today - they most certainly are!
Most of the coming-just-around-the-corner filesystem work appears to be happening on btrfs and Hammer... and based on personal experiences, I wouldn't want to run btrfs in production yet, and Hammer apparently also still has some quirks for the unwary.