| RAID controller news |
Anticipating demise of RAID
controller market...
LSI will Compete with Fusion-io
Editor:-
January 26, 2010 - LSI
and Seagate
today
announced
they have collaborated on designing
PCIe SSDs for the
enterprise accelerator market which will sample in Q2 2010.
Editor's
comments:- LSI approximately the 163rd company to enter the
SSD market (not counting
SSD SoC makers - which
would push the score to about 185).
Partly LSI's move is due to a
strong suction effect from the
SSD market bubble -
and partly an inevitable step given that the high end of the
RAID controller market
is going to disappear.
There's little point in spending money aggregating
IOPS in an
array of hard disks -
if the result costs more, is slower and is less
reliable to
operate.
In Q4 2009 - PCIe was the #1 most popular form factor
for SSD related searches. (Higher than than for
2.5" SSDs.) In
the same quarter the single most popular company profile viewed by readers
was PCIe SSD evangelist
Fusion-io. Dozens of
oems have already entered this market - thereby preparing the educational
framework for user acceptance of this technology.
New Directory for AoE Storage
Editor:- January 15,
2010 - StorageSearch.com
today published a new directory for
AoE (ATA-over-Ethernet NAS
Storage).
Although this
NAS mode first hit our news
pages in 2003 -
support for it has been miniscule and compatible products are only available
from a handful of vendors. Will 2010 be the year that it all changes? Maybe.
SSDs could play a part -
because less latency is wasted in this low level network storage interface.
LSI Samples 600k IOPS ROC for SSD Servers
Editor:-
December 16, 2009 - LSI
announced it is
sampling
the LSISAS2208 - a dual-core
6Gb/sSAS
RAID-on-Chip
IC to OEM customers.
It's
intended to support the forthcoming PCIe 3.0 specification, currently under
development and provide performance levels that meet the needs of
next-generation server platforms based on
flash SSD storage
(up to 600,000 IOPS).
Error Correction in MLC Flash SSD RAID
Editor:-
October 28, 2009 - ECC
Technologies has published a new article which examines
data reliability
issues in RAID systems using MLC flash.
In his survey of
RAID and error correction
related to SSDs the author
Phil White said he thinks that "MLC NAND Flash memories should
implement nonbinary error-correcting codes such as a Reed-Solomon (RS) codes so
that all of the bits from one cell are in one symbol. The communications
industry has been doing that for decades, but the Flash industry has been
implementing a scheme that forces the bits from one cell to be in separate
records (pages) so that one cell failure can cause multiple binary symbol
failures – which seems illogical."
I asked him to expand on
this for our readers.
In reply - Phil said he doesn't think that
most NAND Flash (SSD) companies have a high level of expertise in the field of
error-correcting codes.
"Many of the
NAND Flash controllers
that are out in the market now have ECC Tek's ECC designs in them. None of the
controller companies who have come to us have any idea how to implement binary
BCH encoders and decoders in hardware. I doubt if any of the Flash
manufacturers have that expertise either."
"For years the
Flash manufacturers implemented a simple binary scheme that corrected only 1 bit
in a page. I don't have evidence to prove this, but I believe the NAND Flash
manufacturers simply decided to extend their original scheme to correct N bits
in instead of 1 bit to handle higher error rate devices. I also believe that
they implemented a scheme for MLC NAND Flash to "randomize" the errors
when a cell fails.
"Consider 4-bits/cell. When a cell fails,
0-4 bits may be in error. In order to keep using binary error-correcting codes
that only correct bits, they designed the chips so that all of the bits from
that cell are in different pages.
"To the best of my knowledge, they never considered using RS
codes so that all of the bits from one cell are in one RS symbol. For example,
assume a RS code with 12-bit symbols. Each RS symbol can hold the data from
three 4-bit cells, and if those three cells happen to fail, it will only corrupt
one RS symbol. RS codes can correct t "symbol" errors and s "symbol"
erasures as long as 2t+s is less than or equal to R where R is the number of "symbols"
of redundancy. The most natural and powerful thing to do is to put all of the
bits from one cell in one RS symbol." ...read the article
See
also:- Data
Integrity Challenges in flash SSD Design - a recently published article by
SandForce.
OEMs Qualifying Virtual RAID Adapter Software
Editor:-
September 15, 2009 -
Dot Hill today
announced
that several tier #1 OEMs are evaluating its virtual RAID adapter
software.
VRA-based
solutions enable server OEMs to offer built-in, high-end
RAID functionality in
multi-core Intel compatible servers without the expense of a dedicated
RAID-on-chip acceleration device.
In September 2008, Dot Hill acquired
certain assets from Ciprico
which included exclusive rights to license
RAIDCore
technology from Broadcom.
The acquisition was part of a strategic initiative to offer software-only
products for the enterprise server data protection market as complementary
offering to its existing external hardware RAID array business.
RAIDCore
VRA technology enables RAID to be offered in volume, entry-level servers where
hardware-accelerated RAID has traditionally been too expensive.
Adaptec Ships Flash Cache Backup for RAID Controllers
Editor:-
June 24, 2009 - Adaptec
today announced the availability of
flash
backup options for its SATA/SAS
RAID controllers.
Adaptec's
Zero-Maintenance Cache Protection protects data stored in controller cache for
up to 10 years with no installation, monitoring, maintenance, disposal or
replacement costs unlike lithium batteries.
Editor's comments:-
the industry's 1st flash cache backup module for RAID controllers was
announced in February
2009 by Viking
Modular Solutions.
RAISE Joins RAID lexicon
Editor:- April 15, 2009 -
this week SandForce
has added a new word to the rich
RAID lexicon with their
new word - RAISE (which stands for - Redundant Array of Independent
Silicon Elements).
RAISE is the label for the RAID-like protection
scheme which their
SSD controller uses
inside 1.8"
and 2.5" flash
SSDs.
Although the word is new, the concept is not.
Manufacturers
such as Texas Memory
Systems, Violin Memory
and Fusion-io have
used similar schemes inside their
rackmount SSDs
and PCIe SSDs for some
time.
LSI Announces SSD Aware RAID Features
Editor:- March
10, 2009 - LSI
has announced better support for
flash SSDs in the
latest update to its
MegaRAID
SAS adapters.
LSI calls this feature SSD Guard - which can
anticipate some types of flash SSD failures in
RAID 0 configurations
and starts rebuilding data on a spare unit.
Viking Launches SSD Backup Module for RAID Cache
Foothill Ranch.
Calif. - February 18, 2009 - Viking Modular Solutions announced
ArxCis-NV - a flash SSD based backup for cache memory in RAID controllers.
"Current
technology of backing DRAM modules with batteries provides protection for
approximately 72 hours and also brings a host of battery related issues to IT
managers. ArxCis-NV products help eliminate these issues..." said Adrian
Proctor, VP of Marketing for Viking Modular Solutions.
The ArxCis-NV is a
JEDEC edge compatible
registered DRAM module with ECC which can write to its associated embedded
SSD at 80MB/s triggered by a drop in rail power. The module hold-up power
(typically 10 to 15 seconds, depending upon DRAM density) is supplied by
Supercapacitors, which only require 10 seconds to fully charge. ...Viking profile
|
| . |
| storage history
-
RAID
controllers - 2001,
2002,
2003,
2004,
2005,
2006 |
| . |
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| There
are
hundreds
of articles about SSDs on StorageSearch.com |
Here, below, are some
examples.
- RAM Cache
Ratios in flash SSDs - it's important to know the underlying RAM cache
architecture - even if you're happy with the R/W and IOPS performance.
- 2010 - 1st Fizz
in the SSD Bubble? - even the dogs in the street know this is going to be a
multibillion dollar market. Greed will play as big a part as technology in
shaping the
SSD year ahead.
- the pros and cons of
using SSD ASAPs - auto tuning SSD appliances are a new category of SSD
which entered the market in the 2nd half of 2009 to accelerate servers without
needing human tune-ups. How can you tell if they are right for you? And how
well do they work?
- the Problem
with Write IOPS - in flash SSDs - long established as a useful performance
modeling metric - this article explains why some specs are exaggerated when
applied to flash SSDs - or predict the wrong results for many common
applications.
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Using
SSDs to Boost Legacy RAID and Database Performance - article by Texas Memory
Systems
Adding a solid state disk to inter-operate with an existing
RAID storage system can be like sprinkling fairy dust which makes everything go
faster. That's often cheaper and more effective than upgrading servers and
licenses or replacing existing storage. ...read the article,
Solid state disks | |
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10
Ten Tips for a Successful RAID Implementation
article by Infortrend
In the 20 years since I first worked on
RAID I've read and
published countless articles about this subject.
So what can a new
RAID article tell you?
Plenty of practical stuff - from a modern
perspective. ...read
the article
, ...Infortrend
profile | |
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the
Benefits of SAS (Serial Attached SCSI) for External Subsystems - article by
Adaptec
This introduction to Serial Attached SCSI gives you
an idea of the performance, compatibilities, applications and roadmap for this
new directly attached disk connection standard. With throughput capability
faster than 2Gbps Fibre-channel systems and faster than ultra320 SCSI - the new
SAS products not only provide an upward migration path for parallel SCSI
applications but also open the door to a new class of high performance high
reliability enterprise systems.
...read the article,
...Adaptec profile,
Serial Attached SCSI | |
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The
RAIDn Algorithm - How Does it Compare? - article by Tandberg Data
If
you think you know RAID because you use RAID level 5 and all that ancient
technology from the 1980s then think again.
The newer RAID algorithms
today provide better data survival when you get multiple disk failures and
provide a higher percentage of usable storage. ...read the article,
...Tandberg Data profile,
RAID systems,
RAID controller cards | | |
