hi there, since i am really new to zfs, i got 2 important questions for starting. i got a nas up and running zfs in stripe mode with 2x 1,5tb hdd. my question for future proof would be, if i could add just another drive to the pool and zfs can integrate it flawlessly? and second if this hdd could also be another size than 1,5tb? so could i put in 2tb also and integrate it? thanks in advance adrian -- This message posted from opensolaris.org
> From: zfs-discuss-bounces at opensolaris.org [mailto:zfs-discuss- > bounces at opensolaris.org] On Behalf Of Albert Frenz > > since i am really new to zfs, i got 2 important questions for starting. > i got a nas up and running zfs in stripe mode with 2x 1,5tb hdd. my > question for future proof would be, if i could add just another drive > to the pool and zfs can integrate it flawlessly? and second if this hdd > could also be another size than 1,5tb? so could i put in 2tb also and > integrate it?Absolutely no problem. Just be aware that if *any* of your devices fail, all is lost. (Because you''ve said it''s configured as a nonredundant stripe.) Also, one of the best features of ZFS is automatic checksumming. I love that demonstration where they create a raid set, shutdown, insert the disks into some other system, and start writing random bytes to random sectors ... Put the disks back into the first system and bring it all up. No data errors, because they were detected and corrected. Unfortunately, in a nonredundant configuration, you can only detect errors. Not correct them. So the arguments in favor of adding some redundancy are pretty compelling for all but the most worthless data. In your case, you would only need to add one more disk ... 3x 1.5T disks in a raidz set ... total 3T usable, and 1 disk redundancy.
On Mon, 19 Apr 2010, Edward Ned Harvey wrote:> > Just be aware that if *any* of your devices fail, all is lost. (Because > you''ve said it''s configured as a nonredundant stripe.)The good news is that it is easy to convert any single-disk vdev into a mirror vdev. It is also easy to convert a mirror vdev into a single-disk vdev. This means that you can upgrade your simple "stripe" into a stripe of mirrors. Bob -- Bob Friesenhahn bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
ok thanks for the fast info. that sounds really awesome. i am glad i tried out zfs, so i no longer have to worry about this issues and the fact that i can upgrad forth and back between stripe and mirror is amazing. money was short, so only 2 disks had been put in and since the data is not that worthy i was aware of non-redundancy. though after knowing that "feature" i will surely add a disk for that in the next time. thanks again. adrian -- This message posted from opensolaris.org
> From: Bob Friesenhahn [mailto:bfriesen at simple.dallas.tx.us] > > On Mon, 19 Apr 2010, Edward Ned Harvey wrote: > > > > Just be aware that if *any* of your devices fail, all is lost. > (Because > > you''ve said it''s configured as a nonredundant stripe.) > > The good news is that it is easy to convert any single-disk vdev into > a mirror vdev. It is also easy to convert a mirror vdev into a > single-disk vdev. This means that you can upgrade your simple > "stripe" into a stripe of mirrors.A really good point. Yes, you can take a 2-disk stripe volume, and make a 4-disk stripe of mirrors volume of the same size. No, you cannot take a 2-disk volume, and make it a 3-disk raidz volume. Unless you''re willing to destroy and restore all your data. Also, since the question was "can I expand my volume just by adding more disks" this is worth mention too: Whatever type of volume you have, be it a stripe, a mirror, a stripe of mirrors, a raidz set, or whatever ... You can always expand the volume by just adding disks to it. But if you''re adding non-redundant disks, you''re not fully redundant anymore. If you add a non-redundant disk to some pool that had redundancy, and your new disk dies, then your pool is lost. If you have a raidz volume, of "n" disks, you cannot simply add 1 disk, and have a raidz volume of "n+1" disks. I don''t know if I''m just adding to confusion here. Sorry if it''s not more clear.