Solaris wrote: > You don't have to do it all at once... ZFS will function fine with 1 > large disk and 1 small disk in a mirror, it just means you will only > have the as much space as the smaller disk. >
Sure, but you get no *benefit* until you've done it all, so you "have to" in terms of actually upgrading the vdev size. > As of things now, if you have multiple vdevs in a pool and they are of > diverse capacities, the striping becomes less effective (? not sure > what the right word here is). Each vdev will be capable of being used > to it's entire capacity. > > So suppose in your situation if you have 4 equal disks, configured in > two mirrors. In the future you reach 90% capacity and choose to > upgrade by doubling the size of one vdev. Your pool will use will > strip using the remaining 10% of the original capacity as expected and > then use only the larger vdev from there on. Further in the future if > you then choose to upgrade again by increasing the capacity of the > smaller vdev, the stiping will resume, but there is no way restripe > all of the data evenly across both disks with out copying it off, > removing it and copying it back again. > Well, as I said, I see no realistic risk of pushing the performance limits of a home file server. I get *less* bandwidth through the network than I do from a direct-connected drive, and that's just one single drive. > Overall, I'd would think that if being prepared to upgrade your > entire pool is a concern, that regardless of your zpool configuration > you would want to start saving from day 1 for the upgrade, wait until > the capacity becomes near critical and upgrade the entire pool. This > as opposed to being more reactionary and making a snap decision to buy > what you can afford to bandaid the situation. Afterall, by the time > you get around to upgrading the other vdev's the price/GB will have > dropped even further, assuming you don't replace them with yet even > larger disks than the other vdev. > I certainly expect each vdev to leapfrog the other when upgraded. That was the point. This way I have less paid-for but unused capacity lying around, and given the price and size of disk drives, that's a money-saver. > On 9/27/07, David Dyer-Bennet <[EMAIL PROTECTED]> wrote: > <snip> > >> Sure, that's the same process I have in mind, it's just that you have to >> replace all the disks in the vdev at once to get the new capacity, so I >> felt that sticking to mirrors (meaning only two disks in the vdev) was >> more suitable for my expected future history. >> >> -- >> David Dyer-Bennet, [EMAIL PROTECTED]; http://dd-b.net/ >> Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/ >> Photos: http://dd-b.net/photography/gallery/ >> Dragaera: http://dragaera.info >> >> >> > > -- David Dyer-Bennet, [EMAIL PROTECTED]; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
