Storage devices managed by WildFire's ESS
linearization software are not just faster and
more durable ... they are also less expensive to
build.
Buying a full service all-Flash storage system
is expensive. Prices frequently range from
$3,000 to $5,000 per usable terabyte. For
instance, a 24 SSD Promise JBOD system with
3.84TB SSDs costs $177,000 for 46 to 84
terabytes of usable storage.
Knowledgeable buyers can build Enterprise grade
all-Flash storage using generic software,
choosing between parity RAID (RAID-5 and RAID-6)
and a mirror (RAID-10) of some sort.
A generic RAID-10 system built with
off-the-shelf materials will likely cost $400 to
$600 per terabyte. Write and read
performance will be determined by the quantity
of SSDs present and the performance properties
of these. Typically the 4KB write
performance rate will be the tested performance
of half of the array set. Thus, a 10 SSD
system with 11,000 IOs per second will have a
performance rate of 55,000 4KB IOPS, and a 24
SSD system will have a performance level of
132,000 4KB IOPS.
A generic RAID-5 or RAID-6 system will typically
cost $300 to $400 per usable terabyte.
However, write performance will be much slower
than a RAID-10 system because any random write
requires the read of all other SSDs in the same
RAID-stripe. Accordingly, a parity-based
system normally writes no faster than the write
speed of a single SSD. Thus, in the
example above, the write speed would not exceed
11,000 IOPS whether the array was composed of
two or 24 SSDs.
Conversely, systems managed by ESS and BonFire
cost less, with storage costs as low as $200 per
usable terabytes because ESS-based solutions,
with their linearization of all data, can
deliver high-speed parity-RAID. WildFire's
write speed is the sum of the sequential write
speeds of all the SSDs in the system. For
instance, the sequential speed of 12 SSDs with
520MB/sec of write performance is 6.24GB/sec, or
1.5 million 4KB random blocks per second -
almost 20 times faster than the RAID-10 solution
above..
The same technology which speeds up
WildFire-managed SSDs also radically reduces
write- and RAID-amplification. The benefit
of this varies with the SSD selected.
Enterprise grade SSDs get rid of amplification
problems by providing very high levels of free
space. Read-intensive, commercial, and
4-bit QLC flash normally lack significant free
space. Accordingly, amplification can be
extreme, on the order of 20:1 or even 30:1.
ESS solves the problem and reduces amplification
to a typical level of 1.5:1, making these
classes of media suitable as long-lived mass
storage.
The bottom line in all of this is that ESS and
BonFire give you the ability to use fewer SSDs,
because you don't need RAID-10 for speed.
It also lets you use lower grades of SSD media
by reducing the write amplification of these by
more than an order of magnitude.
