Summary: RAID XL Is Fit For The Mainstream
In most respects, NetCell has actually achieved its declared goal of offering the performance of a RAID 0 simultaneous with the data security of a redundant array mode such as a RAID 5. This is made possible by means of a process that is based on RAID 3 while cleverly widening its bottleneck: RAID XL.
However, first we must emphasize that these levels of performance only work on demanding desktop applications - which is exactly what NetCell wants - not on server applications. Because of the SyncRAID system used - which is based on 64 bit information units - large quantities of data can be read and written for redundancy with little effort.
But this also means that reading and writing smaller data blocks such as those often used by server applications takes more effort, because all hard drives need to be constantly accessed. The result is a considerably reduced number of I/Os per hour.
In the disciplines important for NetCell, on the other hand, the NC-5464 performs outstandingly: with five hard drives, the NC-5464 usually works faster than the competing product from 3Ware. Power output gets interesting when there is a hard-drive crash, because it has hardly any impact on NetCell. Still, RAID XL has one disadvantage: the higher the number of hard drives, the longer access time seems to get.
We think that the most promising configuration right now would be one with three hard drives: There are not many users who can imagine working with two hard drives in RAID 0 for performance reasons. However, a majority of them are afraid of the expense and the increased risk of crashes. On the other hand, a RAID 1 only allows half of the total memory, which means it's rarely an alternative. Four hard drives would be ideal, but then again, only by wasting space in RAID 01 or 10 or with an expensive controller in RAID 5.
RAID XL, on the other hand, seems to be the ideal solution: with three hard drives, the performance of a RAID 0 with two drives can be achieved, while only a third of the total memory has to be sacrificed. This makes it the most interesting variation from the point of view of price.
That's why it will be interesting to see how well the NetCell technology will be received. PCI cards like those provided for testing are conceivable, as are compact and economical solutions for integration on mainboards. With RAID XL, NetCell has in any case smoothed the way toward more efficient use of several hard drives in one PC.
