Hi all, I need to move a filesystem off of one host and onto another smaller one. The fs in question, with no compression enabled, is using 1.2 TB (refer). I''m hoping that zfs compression will dramatically reduce this requirement and allow me to keep the dataset on an 800 GB store. Does this sound feasible? Can I achieve the move to the new box using zfs send/receive? If so, how do I do it? Do I turn on compression on the target host just after I begin the zfs send/receive? thx jake
Jacob Ritorto wrote:> Hi all, > I need to move a filesystem off of one host and onto another smaller > one. The fs in question, with no compression enabled, is using 1.2 TB > (refer). I''m hoping that zfs compression will dramatically reduce this > requirement and allow me to keep the dataset on an 800 GB store. Does > this sound feasible? Can I achieve the move to the new box using zfs > send/receive? If so, how do I do it? Do I turn on compression on the > target host just after I begin the zfs send/receive?Yes, the easiest way is to turn on compression on the dataset above the one you will recieve into. For example if you are receving into tank/home/bob then ''zfs set compression=on home'' will ensure that tank/home/bob inherits the compression setting. -- Darren J Moffat
> Hi all, > I need to move a filesystem off of one host and onto another > smaller > one. The fs in question, with no compression enabled, is using 1.2 TB > (refer). I''m hoping that zfs compression will dramatically reduce this > requirement and allow me to keep the dataset on an 800 GB store. Does > this sound feasible? Can I achieve the move to the new box using zfs > send/receive? If so, how do I do it? Do I turn on compression on the > target host just after I begin the zfs send/receive?How much your data compresses, is dependent on what type of data you have. JPG files won''t compress at all, neither will any other already-compressed file format. But if you have a gene sequence file, it''ll compress 10:1 because it''s so repetitive internally. For typical filesystems, about 70% of original size is a good estimate. Now: If your data will fit into the 800gb drive, it will be tight. And you SHOULD NOT do that. For one, performance of that drive will be horrible, at best. And I''ve heard a trend of horror stories, that zfs has a tendency to implode when it''s very full. So try to keep your disks below 90%.
On Thu, Dec 17, 2009 at 7:11 AM, Edward Ned Harvey <solaris at nedharvey.com> wrote:> And I''ve heard a trend of horror stories, that zfs has a tendency to implode > when it''s very full. ?So try to keep your disks below 90%.I''ve taken to creating an unmounted empty filesystem with a reservation to prevent the zpool from filling up. It gives you behavior similar to ufs''s reserved blocks. $ zfs get reservation,mountpoint tank/reservation NAME PROPERTY VALUE SOURCE tank/reservation reservation 10G local tank/reservation mountpoint none local -B -- Brandon High : bhigh at freaks.com Time is what keeps everything from happening all at once.
> I''ve taken to creating an unmounted empty filesystem with a > reservation to prevent the zpool from filling up. It gives you > behavior similar to ufs''s reserved blocks.So ... Something like this? zpool create -m /path/to/mountpoint myzpool c1t0d0 and then... Assuming it''s a 500G disk ... zfs create -V 50G /path/to/mountpoint/unused zfs create /path/to/mountpoint/importantdata
On Fri, Dec 18, 2009 at 7:44 PM, Edward Ned Harvey <solaris at nedharvey.com> wrote:> So ... Something like this? > > zpool create -m /path/to/mountpoint myzpool c1t0d0 > > and then... ?Assuming it''s a 500G disk ... > zfs create -V 50G /path/to/mountpoint/unused > zfs create /path/to/mountpoint/importantdataOnce you''ve created the zpool, just do: zfs create -o reservation=10G -o mountpoint=none tank/reservation Then just go about creating your normal zfs datasets: zfs create -o mountpoint=/my/important/data tank/importantdata I don''t think that you need to reserve 10% of the total space, but whatever you decide set your reservation value to that. If you change your mind later, you can update the reservation property. -B -- Brandon High : bhigh at freaks.com Suspicion Breeds Confidence