I skimmed the archives and found a thread from July earlier this year about RAIDZ expansion. Not adding more RAIDZ stripes to a pool, but adding more drives to the stripe itself. I''m wondering if an RFE has been submitted for this and if any progress has been made, or is expected? I find myself out of space on my current RAID5 setup and would love to flip over to a ZFS raidz2 solution using 1TB drives, but the lack of efficient expansion with time is really killing the deal. --Bart
I believe there is a plan for expansion by adding devices to a RAID-Z - I was asking this same question a year ago. IIRC: raid-z expansion is in the works. For now, you can add volumes to the zpool. Initially this doesnt sound appealing, but what you can do is this: Let''s say you have 5 1B drives in a raidz2 in a zpool called "mypool". Get 5 more drives, make another raidz2, and add that to "mypool". then you have grown the zpool as well as kept raidz2 protection. the two raidz2 volumes will stripe between each other within the zpool. - - or wait for the device expansion on raidz
Last I heard there were no plans to implement this. I''d like to see it too, but not everyone knows or cares about it. -- This messages posted from opensolaris.org
In the process you describe, you also lose 4GB to parity out of your total of 10GB, don''t you? I''m not sold on the whole add-more-stripes idea. I want to minimize cost while maximizing capacity, and have a slim margin of fault tolerance. Speed doesn''t matter much either since it''s mostly streaming media on there. I think I''ll have to wait for code completion on the expansion trick. --Bart On 23/12/2007, EchoB <echobinary at gmail.com> wrote:> I believe there is a plan for expansion by adding devices to a RAID-Z - > I was asking this same question a year ago. IIRC: raid-z expansion is in > the works. > For now, you can add volumes to the zpool. Initially this doesnt sound > appealing, but what you can do is this: > Let''s say you have 5 1B drives in a raidz2 in a zpool called "mypool". > Get 5 more drives, make another raidz2, and add that to "mypool". then > you have grown the zpool as well as kept raidz2 protection. the two > raidz2 volumes will stripe between each other within the zpool. > - - or wait for the device expansion on raidz > _______________________________________________ > zfs-code mailing list > zfs-code at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-code >
I would like to convert my home system to Solaris 10 + ZFS, but being able to expand a RAID-Z pool one disk at a time is a must for my resources. I can''t be adding three disks at a time for striping across multiple pools; first buying one disk is more affordable, but also because I can''t shove so many disks in my case! It would be great if Sun devs consider adding this feature. Thanks! -- This messages posted from opensolaris.org
This is pretty startling. I just assumed that something like this would work, since most people have growing data needs and adding new pools to a stripe would be a waste of money, space, power, time, etc. I''m glad I read this - I''ll go ahead and buy more hard drives now, though I would rather have waited until prices dropped before adding additional drives that I don''t need. The other reason this is bad from a storage perspective (I would think) is that having all the drives added in to the stripe at once will make them each incur similar usage patterns, increasing the probability that failures will occur at the same time or around the same time. -- This messages posted from opensolaris.org
I''m a little confused. I upgraded my raidz pool from 3 250G drives to 3 500G drives simply by doing a ''replace'' operation on each 250, using a 500 each time as the replacement. Am I missing something here? Blake -- This messages posted from opensolaris.org
You replaced all your drives with bigger ones. The usage scenario being discussed here is if you had bought one additional 250G drive and added it to your existing RAID-Z pool. That''s a pretty big difference and is not possible with the current version of ZFS. -- This messages posted from opensolaris.org
Ok, that makes a lot more sense. I think the battle here is for Sun to realize that a lot of momentum has been gained for MS and Linux by turning out software that satisfies ''small'' needs - like this one. It''s true that few enterprises would view the requested operation as an essential (they''d do what I did and bump up all the drives, or migrate to a new array with zfs send), but to gain mindshare, the feature being discussed would be a major win. Blake -- This messages posted from opensolaris.org
What''s the status of online capacity expansion for RAID-Z? Hardware raid cards still have a leg up in this regard because it negates the zfs''s supposed scalability feature that SMBs are most interested in. For example if you start off with 2 raidz2 vdevs of 5 1TB drives each. Then as required they can be grown by adding additional drives to the same raidz2 vdevs minimizing costs. Creating new raidz2 vdevs would carry an additional 100% cost increase just to increase the pool size by 2TB. -- This messages posted from opensolaris.org
On Thu, May 01, 2008 at 10:21:19AM -0700, Bryan wrote:> What''s the status of online capacity expansion for RAID-Z? > Hardware raid cards still have a leg up in this regard because it negates > the zfs''s supposed scalability feature that SMBs are most interested in. > For example if you start off with 2 raidz2 vdevs of 5 1TB drives each. Then > as required they can be grown by adding additional drives to the same > raidz2 vdevs minimizing costs. Creating new raidz2 vdevs would carry an > additional 100% cost increase just to increase the pool size by 2TB.While Sun has no official plans to implement RAID-Z expansion, Matt Ahrens and I have written up a plan for how one might implement it: http://blogs.sun.com/ahl/entry/expand_o_matic_raid_z If there are members of the community interested in implementing pieces of this, we could set up a project on opensolaris.org. Adam -- Adam Leventhal, Fishworks http://blogs.sun.com/ahl
I wouldn''t know the first thing about how to implement this kind of stuff. But I''m sure there are people who would. I just really need this feature or ZFS is useless in small scale deployment. -- This messages posted from opensolaris.org