Since I'm feeling bored at the moment... On Tue, Apr 02, 2002 at 02:29:28PM -0800, Alvin Oga wrote: > typically a minimum of 2 disks used for raid0 or raid1... > raid1(mirroring) protects against one disk failure > ( one disk's capacity is used as a redundant copy and not for user) > ( 50% lost of space )
Correction: Protects against loss of all-but-one disks. A 10-way mirror can drop 9 disks without losing any data. > raid0(stripping) does not help for disk failures A stripe set is more vulnerable to disk failure than a non-RAID solution. If you're not using RAID, a failed drive only takes out the data on that one disk. With RAID0, a failed drive will cost you most (if not all) of the data on the array. > typically 5 disks for raid5 ... > ( 3 disks mininum -- 1/3 of your disks lost to parity > ( 4 disks .......... 1/4 of your disks lost to parity > ( 5 disks .......... 1/5 of your disks lost to parity Don't know where you got the "typically 5 disks" bit from. RAID5 costs you one drive's worth of capacity. Also, if I were to set up a 5-disk RAID5 for critical data, I'd go with 4 active disks, plus one spare. > typically raid01 - needs 4 disks ... > first data is stripped across 2 disks than its mirrored to 2 more disks > - due to mirroring... 2 disks is lost for "mirror" Minimum 4 disks, but any larger even number of active disks will work. Here again, if dealing with important data, I'd add an odd disk to the array as a spare. > and after its all said and done... pull out a disk (simulated disk crash) > and see if you're data is still intact Yep. It's the only way to be sure. -- When we reduce our own liberties to stop terrorism, the terrorists have already won. - reverius Innocence is no protection when governments go bad. - Tom Swiss -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
