of Symmetrix, the DMX and the V-Max series, do not support RAID S (instead they support RAID-1, RAID-5 and RAID-6.) The ZFS filesystem, available in Solaris , OpenSolaris , FreeBSD and Mac OS X , offers RAID-Z , which solves RAID 5's write hole problem. Hewlett-Packard 's Advanced Data Guarding (ADG)