The installer's requirement that disks be at least half ZFS makes no sense. I wanted to install a modest (100GB) zfs root on a couple 1TB SSDs and reserve the rest of the space for L2ARC and ZIL for of the spinning rust in the box, but the installer doesn't provide a way to leave space unused and refuses to allow more than 50% of the disk to be swap (easily recyclable later). This check seems needlessly paternalistic. This report is actually against 10.3-RC2, but that's not an option in bugzilla.
That conditional was added by dteske, but I see your point. We can remove that condition. In the future, it might make sense to offer the user the ability to leave unused space, but, we were trying not to clutter the UI with too many options. I will propose a patch to RE@ and see what they think.
Created attachment 168330 [details] Patch to remove the 'max 50% swap' conditional
A commit references this bug: Author: allanjude Date: Thu Mar 17 17:53:38 UTC 2016 New revision: 296988 URL: https://svnweb.freebsd.org/changeset/base/296988 Log: Remove 50% ZFS conditional from bsdinstall/zfsboot Remove the requirement that the resulting partition table be atleast 50% ZFS PR: 208094 Requested by: brooks Sponsored by: ScaleEngine Inc. Changes: head/usr.sbin/bsdinstall/scripts/zfsboot
A commit references this bug: Author: allanjude Date: Thu Mar 17 21:49:20 UTC 2016 New revision: 296997 URL: https://svnweb.freebsd.org/changeset/base/296997 Log: MFC: r296996 Remove 50% ZFS conditional from bsdinstall/zfsboot PR: 208094 Approved by: re (marius) Changes: _U releng/10.3/ releng/10.3/usr.sbin/bsdinstall/scripts/zfsboot
The fix has been committed, and should ship as part of 10.3-RC3 that will be released tonight/tomorrow.
I've successfully reinstalled my box with RC3 and got more or less the result I wanted. Being able to specify the amount used by ZFS might be nice eventually.