Richard Elling wrote: > Rainer Heilke wrote: > >>> So, if I was an enterprise, I'd be willing to keep >>> enough empty LUNs >>> available to facilitate at least the migration of >>> one or more filesystems >>> if not complete pools. >> >> >> >> You might be, but don't be surprised when the Financials folks laugh you out >> of their office. Large corporations do not make money by leaving wads of >> cash lying around, and that's exactly what a few terabytes of unused storage >> in a high-end SAN is. This is in addition to the laughter generated by the >> comment that, "not a big deal if the Financials and HR databases are offline >> for three days while we do the migration." Good luck writing up a business >> case that justifies this sort of fiscal generosity. > > > > To be fair, you can replace vdevs with same-sized or larger vdevs online. > The issue is that you cannot replace with smaller vdevs nor can you > eliminate vdevs. In other words, I can migrate data around without > downtime, I just can't shrink or eliminate vdevs without send/recv. > This is where the philosophical disconnect lies. Everytime we descend > into this rathole, we stir up more confusion :-( > > If you consider your pool of storage as a zpool, then the management of > subparts of the pool is done at the file system level. This concept is > different than other combinations of devices and file systems such as > SVM+UFS. When answering the ZFS shrink question, you need to make sure > you're not applying the old concepts to the new model. > > Personally, I've never been in the situation where users ask for less storage, > but maybe I'm just the odd guy out? ;-) Others have offered cases where > a shrink or vdev restructuring could be useful. But I still see some > confusion with file system management (including zvols) and device management. > The shrink feature is primarily at the device management level. > -- richard
I understand these arguments, and the differences (and that most users will never ask for less storage), but there are many instances where storage needs to move around, even between systems, and in that case, unless a whole zpool of storage is going, how do you do it? You need to give back two LUN's in a 6-LUN zpool. Oh, wait. You can't shrink a zpool. Many people here are giving examples of where this capability is needed. We need to agree that different users' needs vary, and that there are real reasons for this. Rainer This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
