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"GEOM, however, supports only RAID0, RAID1, and RAID3. It does not support RAID5 or RAID6 in software RAID configurations!" Looks like the author is still lear
by r3ddaem0n 12y ago
"GEOM, however, supports only RAID0, RAID1, and RAID3. It does not support RAID5 or RAID6 in software RAID configurations!"
Looks like the author is still learning FreeBSD and hasn't read all relevant docs yet. 'man 8 gvinum' clearly says that raid5 _is_ supported:
"To create a raid5 array on disks /dev/ada1 /dev/ada2 and /dev/ada3, with stripesize 493k you can use the raid5 command:
gvinum raid5 -s 493k /dev/ada1 /dev/ada2 /dev/ada3"
I'd take this article with a big grain of salt.
- teddyh 12y agoRAID5 is obsolete. In RAID5, if a disk breaks in an array and is replaced, the system has to read all of the remaining disks to rebuild the array. If a single byte is unreadable on any of those remaining disks, your array can’t be rebuilt and you have lost your data. With today’s disk sizes, the chance of this happening is larger than is acceptable. The interim solution is RAID6, which will work for some years to come.
- Scramblejams 12y agoNot true with mdadm. Yes, your unreadable single byte will translate into a corrupted file somewhere, but I've recovered plenty of mdadm RAID5 and RAID6 arrays that had lost one or both extra drives and suffered from UREs on the remaining disks. Love good software RAID!
- teddyh 12y agoI agree about software RAID – I use it exclusively myself. Also, nice to know that an array can be recovered, even though it would seem to be a reasonable thing to assume, it is good to know that it is possible. But my point was that: 1. You still have some lost data. 2. An RAID5 array which breaks in this way must be manually rebuilt, possibly from a rescue boot media. Your server will no longer even boot up by itself.