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21 Articles, FAQs and Whitepapers about iSCSI

As the iSCSI market grows so too does the number of articles we feature on this important subject. So - instead of cramming all the links into the main iSCSI page - I've created this list of article abstracts.
articles about iSCSI and IP / SAN on
article:- the State of iSCSI, SAS, SATA and InfiniBand (Q3 2006)

5 years after launched dedicated pages to 4 new storage interfaces - we went back to see how successful they'd been in the market compared to their original promise.

article:- the State of iSCSI? (2004)- we interview PyX Technologies

"There is little awareness that iSCSI has different levels for fault tolerance within the protocol or that not all iSCSI-enabled products are fully compliant with the protocol as written." ...PyX Technologies profile

article:- iSCSI take-up in Europe 2004-2005 - by FalconStor

"With the benefit of hindsight, it looks now as though I may have been over-optimistic as to the levels of take-up of iSCSI in 2004 - but, ironically, because I was right: iSCSI has, after all, had to go through a normal evolutionary cycle, and that cycle has simply taken longer than the twelve months I predicted." ...FalconStor profile

article (on archived news) - Running with iSCSI - by FalconStor

"Large organisations see iSCSI deployment as an opportunity to extend the benefits of their datacentre FC SANs to distributed application servers, while mid-sized organisations, often regarding FC as a substantial investment, see an opportunity to get on the SAN bandwagon with a smaller investment." ...FalconStor profile

article:- iSCSI is now a market reality

"iSCSI was the vaporware product of the year 2002. The summer of 2003 has witnessed a couple of important milestones which have changed all that." storage history

article:- Cancer Therapy and Research Center Uses iSCSI Technology - by Datalink (pdf)

"CTRC chose the iSCSI solution to mirror the data because it was more cost effective than "server-to-server" or "storage-to-storage" replication architectures. Plus, it was the only way they could meet their standard to not be down for more than 10 minutes." ...Datalink profile
articles about iSCSI on other sites
article:- Securing Storage Area Networks with iSCSI - by EqualLogic (pdf)

"While firewalls and IPsec protect packets at the IP level, iSCSI provides a request and response login procedure to ensure that only trusted iSCSI initiators can access the storage behind a particular target. When an iSCSI initiator connects to a target, the login procedure authenticates both the initiator and the target and sets iSCSI and security protocols for the session. SCSI commands can be sent only after the login completes." ...EqualLogic profile

article:- FAQS about IP Storage and iSCSI RAID - by StraightLine

"Why use iSCSI or an IP SAN when we have a NAS? - This is a great question. Two big reasons: performance and data access. If you place an iSCSI RAID on the same network as a NAS, the iSCSI RAID will out perform the NAS by about 3.5 times. Please see our performance section. Data access is a broad topic. Backup is much simpler for an iSCSI RAID. Mutliple paths to an iSCSI RAID, ie. through different switches, is a network setup furnction. Using iSCSI in a cluster as a safeguard against host failures is possible." ...StraightLine profile

article:- The Total Economic Impact. of Network Appliance IP-SAN Solutions (pdf)

"Upon implementation of NetApp IP-SAN solutions, each interviewed organization reduced the number of Exchange servers and experienced savings associated with Exchange server hardware, licensing, and management complexity. For our sample organization, we estimate that the licensing, infrastructure, maintenance, and support cost savings associated with a reduction of two existing servers would be $3,500 per server, per year . or $7,000 annually for a total three-year savings of $21,000. Each organization cited the comparative simplicity of managing an iSCSI SAN versus a DAS (or Fibre Channel SAN). Customers indicated that NetApp.s IP-SAN solutions represent simple, scalable, and affordable technology for their networked storage requirements." ...Network Appliance profile

article:- IP SANs to Replace NAS - by SANRAD (pdf)

"This document reviews the advantages and disadvantage of NAS vs. SAN, how NAS vendors address their disadvantages, and introduces an IP SAN solution, which combines any disk storage system with SANRAD's iSCSI V-Switches. This complete IP SAN solution will deliver a better solution than NAS." ...SANRAD profile

article:- iSCSI FAQs - by Network Appliance

"The iSCSI protocol is expected to accelerate the transition from direct-attached storage to networked storage by reducing the costs and complexity traditionally associated with SAN deployment and making it feasible to deploy SAN storage solutions in places where Fibre Channel SANs are not cost-effective."

white paper:- iSCSI FAQs - by Cisco, HP and IBM

This is a much more technical FAQs than the otherswe've linked to. Here's an sample extract:- "Connection reinstatement is the process of an initiator logging in with an ISID-TSIH-CID combination that is possibly active from the target's perspective, which causes the implicit logging out of the connection corresponding to the CID, and reinstating a new Full Feature Phase iSCSI connection in its place (with the same CID). Thus, the TSIH in the Login PDU MUST be non-zero and the CID does not change during a connection reinstatement. The Login Request performs the logout function of the old connection if an explicit logout was not performed earlier. In sessions with a single connection, this may imply the opening of a second connection with the sole purpose of cleaning up the first. "

article:- iSCSI: Networked Storage for the Masses - by HDS (pdf)

"Until the recent emergence of iSCSI - the application of SCSI storage device protocols to conventional IP networks - storage networking remained beyond the grasp of many small and medium-sized companies that could benefit greatly from its advantages." ...Hitachi Data Systems profile

article:- iSCSI FAQs - by Technomages

"Question 9 - Do I need to build a separate network for iSCSI SAN? Answer: No, in most cases you do not. One of the major advantages of iSCSI over Fibre Channel SANs is that it utilizes existing IP infrastructure. In some cases, however, it might be desirable to separate storage traffic into a dedicated network for performance reasons. This is especially true for installations which do not have a Gigabit Ethernet network installed." ...TechnoMages profile

article:- How iSCSI Works - by ArdisTech

"There are a few things you should be aware of when designing an IP SAN, however. First, TCP has some inherent overhead embedded in the protocol. This is necessary when transmitting over unsecured and potentially unstable networks (e.g., the Internet). This overhead reduces performance of the theoretical speeds of Ethernet. Additionally, the faster the implementation of Ethernet, such as 1Gbps, the larger and more frequent the TCP overhead will be on the servers and clients in the network. One major reason folks have had to upgrade their servers when migrating to 1Gbps Ethernet can be traced to the simple fact that they're now handling roughly 10 times the TCP they were before. This can severely cripple, even crash servers that are only a couple years old." ...ArdisTech profile

article:- 4 Common Problems iSCSI Solves - by Adaptec

"iSCSI SANs help IT managers meet their budgetary constraints by allowing them to add storage when needed without having to significantly increase headcount to manage the storage. In addition, the flexibility to add storage on the fly eliminates the guesswork in deploying storage for anticipated growth and allows IT managers to fully utilize the purchased storage." ...Adaptec profile

article:- A Quick Guide to iSCSI on Linux - by Cuddletech (pdf)

"It's important to understand that iSCSI, unlike NAS, makes block devices available via the network. Effectively, you can mount block devices (disks) across an IP network to your local system and then use them like any other block device. Generally when you first use an iSCSI device you're going to need to partition it, label it, and create a filesystem on it. Unlike NAS your kernel will be able to read and write to your new iSCSI device just as if it were a local hard disk and therefore you can use any filesystem you like (EXT2/3, JFS, XFS, ReiserFS, etc). Also, because it is being handled as a block 2 device only one (1) system can use the iSCSI device at a time! (This changes if you use a global filesystem, or read-only filesystem.) So just like Fibre Channel you're not making 4 machines access 1 filesystem, but instead you're allocating 4 chunks of disk on one large device and making it avalible via an iSCSI target so that 4 initiators can access it."

article:- iSCSI Technology - by Crossroads Systems

"The concept of pushing SCSI, or block oriented storage commands, over a serial interface is not really new technology. Fibre-Channel, IEEE-1394 (Firewire) and USB have been doing this for a number of years already. The major difference between these buses and the buses that carry TCP/IP is that IP based buses were never intended to be used as storage transports, which require sequenced ("in order") delivery, guaranteed timing, and robust error correcting." ...Crossroads Systems profile

article:- A beginners guide to iSCSI - by McDATA

"As someone who has worked in Fibre Channel for some years, I am afraid I have to point out to the Fibre Channel world that iSCSI can run at wire speed and certainly can run as fast as any normal server running normal applications. To the IP community, I would like to point out there is a lot of Fibre Channel out there -- particular comparing the numbers with the number of 1GB network ports rather than any network ports. To the Fibre Channel community, I must point out that while a lot of storage and even a lot of high-end servers are connected to Fibre Channel, there are still quite a few Unix servers not connected and the vast majority of the Intel server community is not Fibre Channel connected." ...McDATA profile

article:- Newcomer iSCSI promises to enable the SAN market in ways incumbent Fibre Channel can't - EDN magazine

"Many storage applications call for low latency. How then, does another layer of protocol reduce Ethernet latency? The truth is: It doesn't. Thus, the introduction of the TOE (TCP/IP offload engine), which moves all or part of TCP/IP processing from a host processor to hardware-based processing. TOEs form a key part of the iSCSI story by reducing overall latency and host-CPU usage and allowing the CPU to manage connections from a session rather than a packet perspective."

article:- "I want my iSCSI!" Easier said than done - Computer Technology Review

"The iSCSI protocol is designed to have no single point of failure, to aggregate all available bandwidth and to be tolerant of hardware and service provider failure. Many of these features only operate properly in the upper Error Recovery Levels of the protocol--the same ERLs which most vendors have chosen not to include in their iSCSI stack. Further, if one looks at most of the iSCSI products--many of the iSCSI HBAs and TOEs available on the market today--most have only a single Gig-E port. Even if one installs two of these devices (heat considerations aside, natch), this leaves the problem of aggregation across subnets unaddressed: You still can't get there from here. To properly configure the upper Error Recovery Levels (ERL 2 in particular) one simply must have more than one port on an HBA. This is assuming, of course, one acknowledges that a single port, by definition, creates a single point of failure. " Storage publications
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Nibble:- Re: iSCSI and FCIP

iSCSI (Internet SCSI) is a software package which emulates SCSI protocols, but the connection method is via an IP network instead of a direct SCSI compatible cable.

SCSI is an intelligent protocol which enables data blocks to be read from or sent at high speed to a storage device such as a disk or tape drive. Early implementations of SCSI used ribbon cable and industry standard logic levels.

The idea behind iSCSI is that storage management software which was orginally written for the well established SCSI standard, can now be used to make a remote disk or tape drive on a network operate just like a local disk. The network can be a local area network such as ethernet, or even the Internet. The potential benefit is that users can connect to remote storage devices to replicate data without having to invest in writing huge amounts of new (buggy) software.

Similarly FCIP or Fibre Channel over IP emulates SAN functionality over an internet connection.
how fast can your SSD run backwards?
SSDs are complex devices and there's a lot of mysterious behavior which isn't fully revealed by benchmarks and vendor's product datasheets and whitepapers. Underlying all the important aspects of SSD behavior are asymmetries which arise from the intrinsic technologies and architecture inside the SSD.

Which symmetries are most important in an SSD?

That depends on your application. But knowing that these symmetries exist, what they are, and judging how your selected SSD compares will give you new insights into SSD performance, cost and reliability.

There's no such thing as - the perfect SSD - existing in the market today - but the SSD symmetry list helps you to understand where any SSD in any memory technology stands relative to the ideal.
SSD symmetries article And it explains why deviations from the ideal can matter. to read the article

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