RAID5 metadevices need fewer disks for data redundancy than mirrors, and therefore can cost less than a mirrored configuration.
Is there a maximum number of slices a RAID5 metadevice can have?
No. The more slices a RAID5 metadevice contains, however, the longer read operations take when a slice fails. (By the nature of RAID5 metadevices, write operations are always slower.)
By concatenating slices to the existing part of a RAID5 metadevice.
When I expand a RAID5 metadevice, are the new slices included in parity calculations?
What are the limitations to RAID5 metadevices?
You cannot use a RAID5 metadevice for root (/), /usr, and swap, or existing file systems.
Is there a way to recreate a RAID5 metadevice without having to "zero out" the data blocks?
Yes. You can use the metainit(1M) command with the -k option. (There is no equivalent within DiskSuite Tool.) The -k option recreates the RAID5 metadevice without initializing it, and sets the disk blocks to the OK state. If any errors exist on disk blocks within the metadevice, DiskSuite may begin fabricating data. Instead of using this option, you may want to initialize the device and restore data from tape. See the metainit(1M) man page for more information.