Figure 10-7. RAID 0+1 writes a stripe first, then mirrors the stripe.
CHAPTER 10 n HARDWARE CONSIDERATIONS 252
If a drive is lost with a RAID 0+1 stripe set, it must be replaced by the entire mirrored
stripe set??”a process that may not be instantaneous or straightforward (depending on
how RAID 0+1 is implemented by your vendor).
RAID 10 is better suited for disaster recovery, because it focuses on mirroring each
drive first, then striping them all for performance (see Figure 10-8).
Figure 10-8. RAID 10 immediately mirrors each write to a drive.
If an individual drive is lost in a RAID 10 array, the mirror of that drive will come
online immediately. In fact, it??™s possible to lose multiple drives and have the array still
function as long as you don??™t lose both a drive and that same drive??™s mirror.
RAID 5+1
RAID 5+1 is a single-parity array in which each drive is mirrored. You need a minimum of
six drives for this configuration, as shown in Figure 10-9.
CHAPTER 10 n HARDWARE CONSIDERATIONS 253
Figure 10-9. RAID 5+1 provides excellent protection from drive failure.
With RAID 5+1, it is possible to lose an entire stripe and still keep the array functional.
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