to allow for bootable Veritas VxFS operation. Logging or journaling was added to UFS in Sun's Solaris 7. Releases of Solaris 10, Solaris Express, OpenSolaris, and other open source variants of the Solaris operating system later supported bootable ZFS. Logical Volume Management allows for spanning a file system across multiple devices for the purpose of adding redundancy, capacity, and/or throughput. Legacy environments in Solaris may use Solaris Volume Manager (formerly known as Solstice DiskSuite). Multiple operating systems (including Solaris) may use Veritas Volume Manager. Modern Solaris based operating systems eclipse the need for volume management through leveraging virtual storage pools in ZFS. macOS macOS (formerly Mac OS X) uses the Apple File System (APFS), which in 2017 replaced a file system inherited from classic Mac OS called HFS Plus (HFS+). Apple also uses the term "Mac OS Extended" for HFS+. HFS Plus is a metadata-rich and case-preserving but (usually) case-insensitive file system. Due to the Unix roots of macOS, Unix permissions were added to HFS Plus. Later versions of HFS Plus added journaling to prevent corruption of the file system structure and introduced a number of optimizations to the allocation algorithms in an attempt to defragment files automatically without requiring an external defragmenter. Filenames can be up to 255 characters. HFS Plus uses Unicode to store filenames. On macOS, the filetype can come from the type code, stored in file's metadata, or the filename extension. HFS Plus has three kinds of links: Unix-style hard links, Unix-style symbolic links, and aliases. Aliases are designed to maintain a link to their original file even if they are moved or renamed; they are not interpreted by the file system itself, but by the File Manager code in userland. macOS 10.13 High Sierra, which was announced on June 5, 2017 at Apple's WWDC event, uses the Apple File System on solid-state drives. macOS also supported the UFS file system, derived from the BSD Unix Fast File System via NeXTSTEP. However, as of Mac OS X Leopard, macOS could no longer be installed on a UFS volume, nor can a pre-Leopard system installed on a UFS volume be upgraded to Leopard. As of Mac OS X Lion UFS support was completely dropped. Newer versions of macOS are capable of reading and writing to the legacy FAT file systems (16 and 32) common on Windows. They are also capable of reading the newer NTFS file systems