The SATA/6G standard is needed to eliminate the
channel bottleneck when solid-state devices are
connected to SATA controllers.
I include both flash memory and SDRAM in the term "solid-state devices".
Assuming a worst-case controller overhead of 20%
of rated bandwidth, 4 x SATA/6G channels in RAID 0
are theoretically capable of a combined bandwidth
of 4 x 600 MB/second = 2,400 x 0.80 = 1,920 MB/second.
Call it 2 GB/sec.
Now we're talking greatly improved file system performance,
via standard SATA ports on standard motherboards.
Moreover, compare the above with the theoretical bandwidth
possible with something like OCZ's new "Z-drive", which
uses an x8 lane PCI-Express slot:
http://www.madshrimps.be/?action=getarticle&number=1&artpage=3979&articID=911
8 lanes @ 250MB/sec x 0.8 = 1.6GB/second (in one direction, e.g. READs)
Or, if the Z-drive's controller is measurably faster, use 0.9 controller efficiency:
8 lanes @ 250MB/sec x 0.9 = 1.8GB/second (in one direction, e.g. READs)
However, as seen from the review above, the Z-drive is doing READs
presently at only 600 MB/second. This may see FAST, however it is
not very close to real channel capacities.
So, the decision to go with a device like the Z-drive,
as opposed to 4 x solid-state devices in RAID 0,
will likely turn on the bottom-line cost to achieve
comparable performance.
Where do you think the bottleneck is in this new OCZ Z-drive?
My guess is the flash memory chips, not in the controller
-- a Highpoint RocketRAID 3520:
http://www.highpoint-tech.com/USA/rr3520.htm
In terms of price-performance, a P45 system with 16GB of RAM
or Core i7 system with 24GB of RAM, can be enhanced with a
single copy of RamDisk Plus at $50 - $100, resulting in file system
performance approaching 25,000 MB/second (i.e. Core i7 at stock settings).
Given the rock bottom prices of DDR2 presently,
a 16GB P45 system sounds like an excellent way
to deliver outstanding file system performance
when most recently used files are "cached"
in a ramdisk.
We have already measured 2.7GB/second READs
using a Corsair DDR2-800 that is now 3+ years old
to host a ramdisk using an earlier version of
RamDisk Plus!
For the cost premium of a Core i7 system,
a huge leap in file system performance is
obtained by dedicating an upper subset of
12-24GB of RAM to a ramdisk.
Your thoughts are most appreciated here.
MRFS