Greg, I've been looking at actuators for six years now

Post #33,090 by tonytib 3/21/02 9:46:09 PM Reply	Greg, I've been looking at actuators for six years now plus I've done work for HDD media companies. So I've seen plenty of SCSI parts and IDE parts, mainly actuators and head stacks. And, I can tell you that the basic quality of a Seagate SCSI head stack is better than a typical WD IDE one. That doesn't mean the whole drive is better, since that depends on a lot of factors. Some SCSI and IDE drives only differ interface electronics, but many do not. For example, there is no IDE equivalent to the 10,000 RPM SCSI drives (Fujitsu, IBM, Seagate), let alone the Cheetah X15 (15,000 RPM drive). And, running at higher speed requires quite a few changes. For example, high-end SCSI drives typically have lower areal density than IDE drives. Frankly, I'd like to see solutions that just work. I'm sick and tired of messing with stupid computer components that are a pain to get working. If (or when) I need a RAID (level 5) array, if I can be confident that the SCSI solution will be easy to get working (and be more reliable) than an IDE RAID solution, then I'll definitely consider spending the extra money. Storage Applicance, EMC, etc can spend a lot of time and money figuring out weird permutations in IDE RAID configurations (if Karsten and Andrew's experiences are a guide). I don't want to - and I bet I can build a Linux-based NAS solution with SCSI RAID drives that will work fine for me for a heck of lot less than them -- or even Quantum (SnapServer), etc. Tony
Post #33,100 by folkert 3/21/02 11:05:09 PM Reply	Then why do we never here about... SSA... huh? Current revisions of SSA is extremely fast, Extremely reliable... matter of fact IBM uses them in thier Enterprise Storage Server (ESS - Shark). Lets assume that there are significant reasons why IBM bucks the trends. Lets grant that IBM is all knowledgeable. Lets just wonder WHY SSA isn't as popular in PC servers as they are in RS/6000s. In my extremely NON-Humble Opinion, SSA drives with SSA Raid controllers are Far and Wide the most reliable, fastest, scalable, easy to service, easy to make work, self diagnosing, points you to the problem, SETUP in all the world for Storage. I can remove half the wires connecting the drives... as long as 1 remains connected between all of them SOMEHOW, they are all still available. They have zero degradation in performance in that situation, SSA RAID uses can make SCSI raid pale in comparison (even the mighty Mylex controllers IBM makes do too) So explain to me people choose SCSI over SSA. Based upon you arguements SSA would be the ultimate.... PERIOD. I'll tell you why... everyone has been brainwashed into thinking SCSI is BEST, IDE SUCKS anything else is "esoteric". SSA can sometimes be as much as 200%-600% more expensive than even the fastest SCSI. I have gotten IDE RAID to work as well as SCSI RAID, including failure handling. Some may indicate 3ware having problems, company has some developments coming down the pike that may surprise some of us. They are going to be gaining ground. Now I agree earlier products from 3ware were/are buggy. But they have updated firmware for them... but component failure can't be fixed... Oh well the question remains: Why is SSA not as widely used as it should be? `greg, curley95@attbi.com -- REMEMBER ED CURRY!!!` In 2002, everyone will discover that everyone else is using linux. Linux: Good, fast AND cheap. Failure is not an option: It comes bundled with Windows. ** "Two rules to success in life: 1. Don't tell people everything you know." - Sassan Tat
Post #33,105 by Andrew Grygus 3/22/02 12:06:45 AM Reply	Could be a bunch of reasons: Ownership of IP (Intellectual Property) may restrict the number of vendors. Cost of licensing IP may make alternative vendors uncompetitive, so they don't enter the market. Single source is not wise in most (but not all) cases. Cost may be beyond the point of diminishing returns for the majority of applications, just as the cost of SCSI is beyond the point of diminishing returns for most desktop PCs, but priced just right for midrange servers. Lateness to market may make marketing cost to achieve economical volume too high, limiting the product to only the highest end market. Products are designed for particular markets. IDE was designed very deliberately to reduce cost in volume production. Put the controller on the device, and make it a simple controller. SCSI was designed for greater flexibility and better performance. SSA was designed for very high end systems. You can put 2 IDE devices on a cable, 16 SCSI devices. Even with just two, IDE devices don't share the cable very well. Hell, when I put a fast CD writer and a CD-ROM in the same machine I have to put them on separate IDE cables or I get underruns making copies, and CDs aren't really all that fast. I don't have that problem with SCSI. True, newer IDE drives outperform older SCSI drives (at least if there's only one IDE drive on the cable), but SCSI is a moving target. Soon we will have Serial IDE which will solve the "2 per cable" limit, allow longer cables and greatly improve data transfer speed, but Serial SCSI has already been in development for quite some time and will be there for the more demanding markets. Right now, high performance IDE is operating system dependent because of the special drivers needed. SCSI isn't. You can get high performance out of SCSI even on OS/2. I seriously doubt I could get SSA to work at all with the small business servers I build. True, many SCSI drives are mechanically the same as equivalent IDE drives except for the control circuitry, but many aren't. Different SCSI drives are targeted to different markets. Right now IDE doesn't have that differentiation - it's all aimed at the lowest price market. Trying to force any of these devices into the others' markets is not going to work well. [link\|http://www.aaxnet.com\|AAx]
Post #33,110 by tonytib 3/22/02 1:18:29 AM Reply	Politics, IIRC SSA was IBM's equivalent to FC-AL, and it lost out during standardization wars, IIRC. So a number of people use FC-AL, notably Sun, and FC-AL drives frequently appear on the surplus market (I don't believe I've ever seen an SSA drive) and even at Fry's occasionally, but only IBM uses SSA. I don't know enough to compare FC-AL and SSA, so don't ask. My internal knowledge of hard drive parts is based on the parts I've seen, mainly HSA's. Thus, my quality comments were based on the mechanical quality of the parts I've seen (view from inside), not on interface abilities, reliability, etc. Although I've picked up a fair amount of general knowledge (e.g. from IDEMA magazine, DiskCon, customers, etc), I'm not a hard drive designer. OTOH, I'm pretty sure, for example, that the Seagate SCSI engineers don't know much about the Seagate IDE drives (with the possible exception of the IDE Barracuda models if they share the same hardware). My interests in RAID are unrelated to my work. I'm interested in RAID 5 controllers for home (maybe if the economy picks up) and small business. SSA and FC-AL are too pricey. IDE is a possibility, but I'll have to see a lot of good comments (e.g. on StorageReview.com) before I'll trust 3-ware. Promise and Adaptec are also possibilities. As I said before, I'm tired of PC stuff that half works. BTW, the Mylex SCSI RAID boards appear to be about the same price as the 3-ware IDE controllers. As far as future greatness goes, well, my standard answer is: "I'll believe it when I can see it at Fry's". A lot of products (not just from MS) never make it out of the vapor (Linear Technologies, for example, had an analog chip that they had spec sheets for, advertised, and engineers started to design with -- but the chip never made it to production. So, a common EE rule is "If it's not in the DigiKey catalog, don't use it.") Tony

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