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Demartek publishes free 86
page iSCSI guide
Editor:- May 31, 2011 - Demartek has
published an
iSCSI
Deployment Guide (86 pages pdf) aimed at users in Windows environments.
The
company says
- "This guide is intended to be used as a reference and is divided into
sections including iSCSI marketplace data, iSCSI technology areas, and specific
vendor products in the area of network adapters and storage targets. There are
screen shots and information from actual deployments of these products."See
also:- iSCSI SSDs
SSD market waves blog
Editor:- May 31, 2011 - a new
SSD blog by Woody
Hutsell discusses
application
acceleration - particularly in the Oracle market.
Woody says "As
I have argued before, the use of flash hard drives in enterprise arrays is
really about accelerating infrastructures more than about accelerating a
specific application."
WD's acquisition of Hitachi GST on track for Q4
Editor:- May
30, 2011 - Western
Digital today
announced
its proposed acquisition of Hitachi GST is
progressing through EU anti competition review processes and is anticipated to
close in the 4th quarter of 2011.
TMS optimizes SSD architecture to cope with flash plane failure
Editor:-
May 26, 2011 - a new slant on
SSD reliability
architectures is revealed today by Texas Memory Systems
who explained how their patented Variable Stripe RAID technology is used in
their recently launched PCIe SSD card - the
RamSan-70.
TMS
does a 1 month burn-in of flash memory prior to shipment. (One of the
reasons cited for its use
of SLC rather than
MLC BTW.)
Through its QA processes the company has acquired real-world failure data
for several generations of flash
memory and used this to model and characterize the failure modes which
occur in high IOPs SSDs.
Most enterprise SSDs use a simple type of
classic RAID which groups
flash media into "stripes" containing equal numbers of chips. RAID
technology can reconstruct data from a failed Flash chip. Typically, when a chip
or part of a chip fails, the RAID algorithm uses a spare chip as a virtual
replacement for the broken chip. But once the SSD is out of spare chips, it
needs to be replaced.
VSR technology allows the number of chips to
vary among stripes, so bad chips can simply be bypassed using a smaller stripe
size. Additionally, VSR provides greater stripe size granularity, so a stripe
could exclude a small part of a chip rather than having to exclude an
entire chip if only part of it failed - "plane error". With VSR
technology, TMS says its SSD products will continue operating longer in the
installed base.
Dan Scheel, President of Texas Memory Systems explained why their
technology increases reliability.
"...Consider a hypothetical
SSD made up of 25 individual flash chips. If a plane failure occurs that
disables 1/8 of one chip, a traditional RAID system would remove a full 4% of
the raw Flash capacity. TMS VSR technology bypasses the failure and only reduces
the raw flash capacity by 0.5%, an 8x improvement. TMS tests show that plane
failures are the 2nd most common kind of flash device failures, so it is very
important to be able to handle them without wasting working flash."
Editor's
comments:- by wasting less capacity than simpler RAID solutions - more
usable capacity remains available for traditional
bad block
management. This extra capacity comes from the over provisioning budget
which figure varies according to each SSD design (as discussed in my recent
flash
iceberg syndrome article) but is 30% for TMS.
IO Turbine goes into beta
Editor:- May 24, 2011 -
IO Turbine
today announced that its flash SSD supporting acceleration software for VMware
environments is now available for beta testing .
IO Turbine says that
its Accelio product learns what is most important to cache and
transparently offloads
IOPS from
primary storage to flash, delivering performance directly to designated virtual
machines.
Editor's comments:- I probed into the company's
claim that its Accelio (ASAP
software) works with "all" types of flash SSD - because it seemed to
me that it might work well with some interfaces and not very effectively with
others - depending on the pattern of its R/W activity. This is the reply I got
from a company spokesperson.
"Thanks for your question Zsolt. You
are correct in that a PCIe
device will be faster than a
SAS/SATA device and that is a
function of the device, not Accelio. Accelio will work the same regardless.
Accelio is Flash and SSD agnostic and will work with any of these devices. The
value of Accelio is that is can utilize any of these devices within the host to
accelerate virtualized applications without sacrificing the ability to vMotion
to another host if desired. The performance delta, and hence the value
proposition, for Accelio is based on solid state devices in the host versus
spindles over the network. Lastly, if for some reason the Flash/SSD device were
to become slower than the primary, we will send the I/O directly to the primary
storage."
share price indicators rank Fusion-io above STEC
Editor:-
May 24, 2011 - speculation about the current market value of Fusion-io has been
satisfied by
reports
today that the pricing of the company's
IPO
projects a value around $1 billion.
That's also 3x the price
recently paid to acquire
Pliant Technology.
...Later:-
within a month of going public Fusion-io's market cap got close to $2.5
billion! |
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