NCQ enabled SATA drives

[sdadept]

companies have been announcing these since the beginning of the year, however, there are no drives yet available short of possibly the Raptors. Anyone know when NCQ enabled SATA drives are going to be available to the whitebox crowd?

also, is that new intel chipset supposed to work with the NCQ drives in raid configurations?

 

[tdg]

The only NCQ enabled drives that I know of coming out are going to be the Seagate 7200.8 and the Maxtor MaxLine III. The Raptor will probably eventually get it, but they're still using PATA<->SATA bridges, which can only support TCQ, NCQ cannot work without a native SATA interface.

 

[defakto]

um, the raptor 36 and 74 both support command queing...so is there a difference between that and NCQ?

*edit of previous statement

Per western digitals website only the 74 gig drive has command queing

# Enterprise-class throughput – includes Western Digital's Ultra/150 Command Queuing technology that optimizes the sequence of data transfers to the hard drive from the host, providing increased data transfer efficiency resulting in higher performance for enterprise applications. (74 GB drive only)

 

[Ice Czar]

Command Queing @ Lost Circuits
What are the differences between Legacy Command Queuing and SCSI Tagged Command Queuing?
Queuing Schemes: Parallel ATA vs.Serial ATA (including NCQ)
Different Queues in Different Standards

SCSI Tagged Command Queuing is the most sophisticated version of command queuing by means of different types of queue serving different purposes. The versatility of the SCSI implementation is largely based on the ITLQ nexus tag to keep track of workloads, targets, hosts and anything related to the above. Therefore, it would appear as if SCSI will remain the storage solution of choice for complex systems and new command schemes evolved over the past few years, including simultaneous reads and writes through dual ported drives, have increased its lifespan – at least in the enterprise sector – another few years. On the other hand, within the desktop sector or even in small storage networks, SCSI may not be able to play out its technological superiority.

Native Command Queing, Intel \ Seagate Whitepaper

as mentioned its not just the drive and protocol, but the controller as well
the whole scheme is still sorting out, and strides are being made for NCQ to approach SCSI TCQ
and with SAS on the horizon I'll leave this now to more knowledgable members

 

[defakto]

Hey, no need to be condenscending just becuase I haven't been a forum member for that long, or because I'm not totally up to date on the latest protocols being proposed and planned. You spend a year in a combat zone and stay up to date on technology and see how easy it is.

Otherwise, good read on that paper and thanks for the link to it.

 

[Ice Czar]

no need to be condenscending .

you asked a question, and forgot to post your resume
besides I always post keeping in mind the people who arent directly involved in the thread
the lurkers and searchers

 

[sdadept]

so nobody seems to know yet when they are actually going to be available. Anyone? I want to buy a few of the seagate 7200.8 drives. When though!?!

 

[ehZn]

Straight from Tom's Hardware

It won't be available before Q3 this year, but the new Barracuda 7200.8 is likely to be a remarkable drive. With capacities of 400, 300 and 250 GB, these will offer much more storage space than most hard drives available today. Also, it will be the first generation of desktop drives to be equipped with 16 MB cache memory. 8 MB versions are expected to be available, too. With 8.0 ms, the seek time remains in keeping with the current generation 7200.7.

There is, however, one feature that clearly differentiates the Seagate Barracuda series from the Hitachi, Maxtor and WD models: It remains the only native Serial ATA drive. Also, most competitors like Hitachi and WD support classic command queuing called TCQ (Tagged Command Queuing), while Seagate was the first to implement NCQ (Native Command Queuing). Tagged Command Queing is a feature that allows hard drives to tag commands and reorder them in order to reduce latencies. Native command queuing, on the other hand, allows for longer queues and has less overhead.


Looks like you might be waiting a bit longer. Everything I read says q3 this year.

 

[Ice Czar]

Id qualify that as ATA TCQ will have shorter queues than NQC

Queue Depth against The Rest Of The World

Each command that is “queued” also needs to be tracked by its initiator/target/logical unit/queue (ITLQ) nexus tag value to keep record of what has been finished and what is still outstanding in terms of device X to host Y transfers. This is where the term SCSI Tagged Command Queuing (TCQ) originates. Because of the complexity of the ITLQ nexus, SCSI needs to support a queue depth of up to 256 levels, equivalent to 256 individual pipeline stages or outstanding commands.

Desktop ATA specifications only support up to 32 levels, which is more than enough, especially in view of the fact that most consumer operating systems will not even support more than a few outstanding commands. Moreover, piling up of outstanding commands can easily lead to a bottleneck situation, which then proliferates throughout an entire workload session, not to mention the price overhead in the case of commodity drives.

In SCSI, the situation is different altogether, and the biggest difference is actually the fact that a SCSI RAID storage box will appear to the system as a single device. Therefore, the individual queue depths of all devices will combine into a single, extra-deep queue. Conversely, this means that even if the queue depth per device is limited to 32 levels, they can still combine to up to 256 levels. It is rather obvious, though, why on the device level (the Logical Unit in the ITLQ acronym) a 32 stage pipeline is as deep as what is reasonable to support by any supersystem.. Furthermore if queues are deeper, they will fill up at one point and that means a higher number of outstanding commands, which again could result in a bottleneck situation. Keep in mind that a poorly implemented queue is not worth the silicon it is made from.

if we are lucky UICompE02 will drop by and compare ATA TCQ, NCQ, SCSI TCQ and the emerging SAS scheme