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#41
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You're still good for a laugh.
You know you're right. All raid controllers and all drives are exactly identical and reliable. All drivers and software are eqaully reliable so all you have to do is find it. $400 buys you a high end raid card All raid levels are equally well implemented in all controllers It's OK when raid has problems 'cause there's always data recovery a TB of data is just as easy to recover as a few gigs It's always easy or not important to find small problems hiding in a TB of data the only problems drives ever suffer is immediate and sudden failure it's smart to "backup" on the same drive and machine as the data you use speed and capacity are the only criteria everyone should use in choosing storage. You're really funny. At first I thought you were a troll but it's clear your just some kid shooting his mouth off cause he just got a promise card for his bday. If you put together "you bet your job" solutions you wouldn't be able to even jokingly imply these things. And yes "Home" use gets nearly as serious when you have that much data (for a single user to create, manipulate, & manage anyway) that is so important that you are nervous about the backup strategy. For the OP I again say a good backup strategy is what you need and not raid. If you feel you NEED to have raid it is generally uneconomical to not do it "right." Since I'm not responsible for your data feel free to try whatever pleases you. If your needs are more basic than I have been assuming, nearly anything will do, just like for "kony." |
#42
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On Thu, 18 Nov 2004 23:30:00 GMT, Curious George
wrote: You're really funny. At first I thought you were a troll but it's clear your just some kid shooting his mouth off cause he just got a promise card for his bday. yawn, more vague marketing drivel snipped Still no evidence? Did you feel that your post was a substitute? [HINT] It's not. [/HINT] I realize that with no evidence you can't possibly stay on-topic more than providing marketing-style blurbs, but someday if you have enough data you may realize that there is no substitute for redundancy, and all the most expensive SCSI (err, "Do it right" solution) does is limit the amount of redundancy that the budget allows. Suppose there is no budget, the sky is the limit... is SCSI then the best choice? Possibly due to the higher number of drives supported, none of the BS you claimed, but even more important would be the ability to pay salary for an administrator that knows a few FACTS instead of just nonsense marketing, so they can effectively maintain it without needing to rely on the "support" you claimed was a benefit of your proposed solution. Well I'm done with this thread, feel free to throw a few more off-topic insults at me instead of providing any real evidence. |
#43
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Short list of reliability/useability concerns I have with ATA Raid:
- multiple issues surrounding disk write back cache - quality control /more lax component rejection levels - cable issues with PATA - lacking advanced features with most PATA cards - SAF-TE compliance - NVRAM use for transactions - on board thorough diagnostics & NVRAM logging - Continuous background defect scanning by drives & controller - lack of write verification or parallel transactions in RAID 5 - lack of RAID 3 or 4 as more secure alternative to RAID 5 - I question full verification in some RAID 1, 10 - multiple drive firmware issues - really good Linux & Novell support - ability to flash upgrade without reboot - Online array conversion/expansion - ECC ram, battery backup, 64/33 pci - support in the form of highly stable & tested software and replacement with new rather than used parts with prompt turnover & reps who would be actually able to tell you basic low level details about how _their_ raid levels are implemented - SNMP traps, hot swap, hot spare, etc. - redundant dedicated fail-over or cache-mirroring paths A few of the newest and best SATA cards deal with a lot/most of these issues. A company like LSI is porting decent scsi raid technology to ATA inherited from Mylex, IBM, & Buslogic. The main key is that it is new & unproven whether there are unforseen kinks tripping up aspects of the port. For example the MegaRAID SATA 300-8X looks pretty serious but it is a "first to market" SATA 2 implementation. Other Hybridized ATA-only raid 'levels' from other companies are too new to trust. It is all just too new to be seen as a "tried & true" for someone totally nervous about their data. On Fri, 19 Nov 2004 06:47:46 GMT, kony wrote: yawn, more vague marketing drivel snipped What you snipped was the summary of your core assertions & inferences- all of which are flat wrong & you clearly still endorse. Identifying your lack of knowledge is not "vague marketing drivel." What IS "marketing drivel" are notions like "raid 5 is raid 5" or "a drive is a drive" or "having redundant data always yields complete protection." If drive reliability was the only factor, and all drives were equal, than all scsi or fibre arrays would be significantly less reliable per MB than all ATA (according to array MTBF calculation). The increase in I/Os would be severely offset by likelihood of multiple failures. It's simply not the case that say a Promise external box is greatly more reliable than a scsi or fcal array in say a netapp or clariion. "Reliability" is a non-specific and relative term. The prevailing MTBF characterization of "array reliability" is both problematic & inadequate. (You seem to be inferring MTBF is equal without providing any specific numbers or even really any specific characterization of your reliability criteria or measurement.) Reliability as it applies to user expectations about a running system include not only a MTBF-type characterization but also the extent to which data integrity is preserved (even with odd kinds of failure & rare transient error) and also to some extent it overlaps with overall data availability (including maintenance and build convenience features/aspects). Time down or with restricted use during maintenance means the raid has failed to fulfill its primary purpose (availability). Just because you can fix a problem doesn't mean you may still see the thing as 'reliable' (because while you fixed it it was not). Time is valuable, even "free time." Doing it "right" means using mature technology which is sophisticated enough to adequately deal with all "reliability" needs over and above basic fault-tolerance for certain limited events. Yes 'Historically' there were no viable ata alternatives to scsi/fibre. Very recently the best of current sata products seem to be closing the gap with better scsi products, but it is not clear that the gap is fully closed or if there is enough of a track record to truly say they are equal. If that is what you want me to "prove" with "specifics" it belongs in a new thread. Throwing light on your incorrect assumptions, rudeness, and lack of knowledge have already taken us too far away from 'which sata raid 5 cards are full firmware/ghost compatible.' I'll say again it is always a _safe_ recommendation to say that if you are VERY nervous and unforgiving when it comes to data you should steer clear of "entry level" or "first-to-market" products. Furthermore I am also suggesting avoidance of raid 5 except in the best implementations and even then with caution. A suggestion like scsi raid 1+0 causes someone to rethink their operating and backup strategy (without raid) or consider how much data do they actually NEED to be so nervous about to _require_ RAID. If you really have evidence that all raid implementations are equal & all drive failure & error rates and tolerance of failing media, transient error, power failure, etc. are the same I'd still like to see some real comparative evidence (in a new thread). The group would benefit from a substantive comparison that would explain your belief and demonstrate you are familiar with _both_ product types. "You're wrong' & 'I don't like your details or explanation' is hardly an argument or a position to fight for. That's what makes you sound like a child. If I'm so stupid, then educate me. Ranting just scares ppl away from the thread. Pretending I am unclear or vague convinces no one that you have a real, valid position or even that I am wrong. |
#44
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On Sun, 21 Nov 2004 21:35:21 GMT, Curious George
wrote: Short list of reliability/useability concerns I have with ATA Raid: - multiple issues surrounding disk write back cache - quality control /more lax component rejection levels - cable issues with PATA - lacking advanced features with most PATA cards - SAF-TE compliance - NVRAM use for transactions - on board thorough diagnostics & NVRAM logging - Continuous background defect scanning by drives & controller - lack of write verification or parallel transactions in RAID 5 - lack of RAID 3 or 4 as more secure alternative to RAID 5 - I question full verification in some RAID 1, 10 - multiple drive firmware issues - really good Linux & Novell support - ability to flash upgrade without reboot - Online array conversion/expansion - ECC ram, battery backup, 64/33 pci - support in the form of highly stable & tested software and replacement with new rather than used parts with prompt turnover & reps who would be actually able to tell you basic low level details about how _their_ raid levels are implemented - SNMP traps, hot swap, hot spare, etc. - redundant dedicated fail-over or cache-mirroring paths A few of the newest and best SATA cards deal with a lot/most of these issues. A company like LSI is porting decent scsi raid technology to ATA inherited from Mylex, IBM, & Buslogic. The main key is that it is new & unproven whether there are unforseen kinks tripping up aspects of the port. For example the MegaRAID SATA 300-8X looks pretty serious but it is a "first to market" SATA 2 implementation. Other Hybridized ATA-only raid 'levels' from other companies are too new to trust. It is all just too new to be seen as a "tried & true" for someone totally nervous about their data. On Fri, 19 Nov 2004 06:47:46 GMT, kony wrote: yawn, more vague marketing drivel snipped What you snipped was the summary of your core assertions & inferences- all of which are flat wrong & you clearly still endorse. Identifying your lack of knowledge is not "vague marketing drivel." What IS "marketing drivel" are notions like "raid 5 is raid 5" or "a drive is a drive" or "having redundant data always yields complete protection." If drive reliability was the only factor, and all drives were equal, than all scsi or fibre arrays would be significantly less reliable per MB than all ATA (according to array MTBF calculation). The increase in I/Os would be severely offset by likelihood of multiple failures. It's simply not the case that say a Promise external box is greatly more reliable than a scsi or fcal array in say a netapp or clariion. "Reliability" is a non-specific and relative term. The prevailing MTBF characterization of "array reliability" is both problematic & inadequate. (You seem to be inferring MTBF is equal without providing any specific numbers or even really any specific characterization of your reliability criteria or measurement.) Reliability as it applies to user expectations about a running system include not only a MTBF-type characterization but also the extent to which data integrity is preserved (even with odd kinds of failure & rare transient error) and also to some extent it overlaps with overall data availability (including maintenance and build convenience features/aspects). Time down or with restricted use during maintenance means the raid has failed to fulfill its primary purpose (availability). Just because you can fix a problem doesn't mean you may still see the thing as 'reliable' (because while you fixed it it was not). Time is valuable, even "free time." Doing it "right" means using mature technology which is sophisticated enough to adequately deal with all "reliability" needs over and above basic fault-tolerance for certain limited events. Yes 'Historically' there were no viable ata alternatives to scsi/fibre. Very recently the best of current sata products seem to be closing the gap with better scsi products, but it is not clear that the gap is fully closed or if there is enough of a track record to truly say they are equal. If that is what you want me to "prove" with "specifics" it belongs in a new thread. Throwing light on your incorrect assumptions, rudeness, and lack of knowledge have already taken us too far away from 'which sata raid 5 cards are full firmware/ghost compatible.' I'll say again it is always a _safe_ recommendation to say that if you are VERY nervous and unforgiving when it comes to data you should steer clear of "entry level" or "first-to-market" products. Furthermore I am also suggesting avoidance of raid 5 except in the best implementations and even then with caution. A suggestion like scsi raid 1+0 causes someone to rethink their operating and backup strategy (without raid) or consider how much data do they actually NEED to be so nervous about to _require_ RAID. If you really have evidence that all raid implementations are equal & all drive failure & error rates and tolerance of failing media, transient error, power failure, etc. are the same I'd still like to see some real comparative evidence (in a new thread). The group would benefit from a substantive comparison that would explain your belief and demonstrate you are familiar with _both_ product types. "You're wrong' & 'I don't like your details or explanation' is hardly an argument or a position to fight for. That's what makes you sound like a child. If I'm so stupid, then educate me. Ranting just scares ppl away from the thread. Pretending I am unclear or vague convinces no one that you have a real, valid position or even that I am wrong. Well I still don't agree but feel this additional post you made was much more useful than those prior. However a lot of the things you're promoting are not typically needed for the environments you're suggesting as good candidates for the "do it right... SCSI RAID solution". No immature technology is a good choice and yet there is no assurance that any particular, specific SCSI controller tech is more mature than an ATA.. but it was never meant to be a direct comparison between the two, rather than "reliability" is NOT the same thing as features. I've already posted that I was done with this thread but posted again only to compliment you on taking the time to more cleary express your concerns with the differences... regardless of whether I happen to agree with them in the context used. |
#45
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I'm glad we're both calmer now and can come together for real
discussion. I don't expect everyone to always agree with me and that's fine. This is just one last time to make sure I'm fully understood. I sometimes wonder if my longer posts are counter-productive since they're not really geared to the reading/writing style of Usenet. I also think we got a little more into word parsing than ideas and drives rather than raid. I'll try to not to be too long or repetitive. (without promises) On Sun, 21 Nov 2004 23:51:40 GMT, kony wrote: Well I still don't agree but feel this additional post you made was much more useful than those prior. However a lot of the things you're promoting are not typically needed for the environments you're suggesting as good candidates for the "do it right... SCSI RAID solution". My _opinion_ is that if you don't NEED _extremely_ high availability or _absolute_best_ data integrity protection you probably don't need RAID. If you do NEED RAID than it should be a "top-notch" implementation or not to bother. I say this primarily because just because a card or software generates redundant data it isn't necessarily a foolproof fail-safe that will end up saving you time & effort down the line or increase performance. Granted I could probably take "ability to flash upgrade without reboot" & "redundant dedicated fail-over or cache-mirroring paths" off the list - but I'm not sure I would take much more off even though its for home or SOHO use. I guess its fair to expect some disagreement on this. I will characterize Linux, Novell, and SNMP support as 'optional' - depending on the home network. Partial explanation/support: RAID requires a decent chunk of time doing research about it & products, experimenting with stripe size, levels and other configuration options, observing behavior/speed, testing recovery scenarios/strategy (& that's in the best case scenario without compatibility problems or discovering bugs). Overall productivity & free time goes down significantly if you spend a lot of time setting up and administering something you totally don't need or as insurance for an event that may never happen during a short service life, or which may be ill-prepared for certain failures you are unlucky enough to have - all while reducing overall storage MTBF characterization. The RAID must therefore deliver a very significant timesavings & data protection benefit to offset this initial time, $$ investment (incl parts, additional electricity, building in a better box, etc.) and risk from increased complexity. No product can be seen as "reliable" if it has difficulty or potential difficulty meeting its core purposes/promises (in this case it is a data security/reliability/availability/performance 'boosting' product). Because the standard of function that must be met in order for it to "keep all it's promises" is so high there is much less of a problem of something being overkill than insufficient. Being able to get a bunch of drive to work together and generate ECC data is not really the whole poop. Don't get me wrong RAID can be fine to use anywhere - even in home - if you are comfortable with it and have very valuable/limited time relative to data quantity so it has enough potential to be of real help. But I just can't make that same big distinction between few users/home & many users/business for general "reliability". For the most part availability is availability and for the whole part data integrity is data integrity regardless. You may have less users relying on the data but you also have less human resources to manage and secure it. Time is just as valuable when you're home. It's probably more valuable because there is so little of it. (and yet I keep typing...) Call me paranoid but I'm also always suspicious of products with big promises that try to lull me into a sense of security esp when there are huge price discrepancies (& I mean suspicion across the whole price range). No immature technology is a good choice True. and yet there is no assurance that any particular, specific SCSI controller tech is more mature than an ATA.. No assurance- well OK. That's why I've been qualifying "better scsi" or the "best scsi products" instead of claiming "all". "Mature" is a tricky word 'cause it implies two things. 1. Track record: With many scsi product lines it's hard to argue "track record" because the companies got bought out so often so the product lines are interrupted. With others it is easy and they win hands down. 2. In terms of "robustness" most scsi beat all ata hands down until rather recently. Now its more case by case- except at the top tier (like some reputable san stuff, etc) which blows away the best SATA hands down. Now there is currently a place for SATA RAID in the enterprise, but it's mainly near-line storage, caching for tape libraries, etc. It's a hard sell for more important roles partly for performance and partly for not yet being "tried & true." Robustness is generally hard to convey and compare for a client who isn't already confident in a "track record". If a company (like LSI for example) is simply migrating the same technology from SCSI to ATA it is the same & just as "mature" (as far as "robustness" but not "track record")- provided, of course that the entire feature set is ported and there are no kinks in the process that haven't yet been worked out or cause them to make very large revisions/redesigns. Implementation of RAID levels is for the most part proprietary; it isn't entirely standardized. So I still think different offerings merit close scrutiny esp. from companies who haven't done this type of thing before for 'enterprise' use- so their ATA raid design goal from day one could very well be to sell cheap, sexy storage to 'enthusiasts' and they therefore feel different customer obligations and pressures. (I can hear the flame being typed now) There also is one or two mutant raid levels only available on ata which makes me weary of their claims of "robustness" as there is basically is no track record and its a hard comparison. If they are indeed bad "disk quality" will have nothing to do with array "reliability" in those cases. You may not agree but for personal storage, apart from certain performance and design differences, quality control is relaxed because of the relative tradeoff in profitability / defect rates. For ATA drive manufacturing the percentile component rejection rate is generally around 5x less rigorous than scsi drives. Since ATA drives ship at a rate of around 6 to 1 over scsi, that amounts to a huge difference in total questionable units. I don't know which components tend to have higher failure rates and which supply sources are less reputable and how that fits to individual lines. Trying to pin this down more specifically without discussing 'inside information' is not really possible. I can only legitimately talk about anecdotal experience about operational success- which is what I meant early in the thread when I talked about experiential vs engineering info in relation to you contention about drive quality & reliability. Of course independent reliability surveys put both kinds of devices all over the map. That's why I didn't say all scsi drives are more reliable than all ata ones and tried to focus on a line I've had good experience with which is corroborated by "independent" parties (to try to synthesize a somewhat representative sample). This 'quality' difference makes sense for many pro vs consumer products because with larger profit margins you can afford to tighten quality control as well as employ better programmers and engineers and devote more resources to testing & development, etc. In addition you have more savvy customers who demand more from the products who you have to satisfy with more conservative products from a reliability standpoint. You're right, though, that there is no _assurance_ that companies will always "do the right thing" for their consumers and the "top of the line" is often exploitative of consumers with deep pockets. Furthermore less units are produced so the actual difference in profit margin isn't exactly what it outwardly appears. Believe me though you don't want a bad _batch_ of drives in an array. Having drives that are less susceptible to dings and vibrations and quieter (generally FDB over rotary voice coil) more geared to heavy constant use, and with advanced features to preserve data integrity (like background defect scanning), and with flexibility to make the raid work better/more compatible like upgradeable firmware and mode page settings all come together to make a more robust "do it right" type solution with scsi drives. (of course you first have to agree with my cost/benefit overview to see the necessity for this & specific recommendations should indeed change as available product attributes change) but it was never meant to be a direct comparison between the two But we have to compare the two in order to settle your objection to a good scsi RAID 1 (or variants) using a well regarded scsi drive family is a safer bet towards the reliability end over ATA offerings as well as whether ATA and SCSI drive quality & reliability are equal "there isn't some unique failure point or 'lower quality' part on ATA drives that makes them more susceptible to failure." As far as the initial recommendation - I could have also included RAID 3 & 4 but it requires better HW. I didn't mention exact cards because with the price it kinda depends on whether what falls in his lap is acceptable. I also wanted to slow him down because a "newbie" looking for cheap raid 5 is in for surprises as he learns more about raid. "reliability" is NOT the same thing as features. Yes in terms of semantics. No in terms of the idea I'm trying to convey. We're going to have to agree to disagree on this point. If you have to fiddle with it or take it down once in a while it is not "reliable" because it is not meeting its main purpose of very high availability. Likewise without a full feature set that ensures data integrity it would not be "reliable" when or if corruption is generated during disk failure, power failure, flaky devices, noise, or whatever the specific vulnerabilitie(s). It also isn't "reliable" if you are operating with a controller problem & there are no diagnostics to pick it up (I have personal experience with diagnostics mitigating loss) or with a bad configuration backup/restore features that interfere with getting an array back on-line - (availability expectations/time expense). You get my point - I won't go through every line item. The main problem is that array "reliability" is inversely related to # spindles and also by the same calculation lower than a single disk. These "features" that combat _all_ the reliability concerns are vitally important for raid to bring real benefit over a single disk and enough benefit to justify _all_ inherent costs. I've already posted that I was done with this thread but posted again only to compliment you on taking the time to more cleary express your concerns with the differences... regardless of whether I happen to agree with them in the context used. Thank you for taking the time to read my post and comment on it putting aside our harsh disagreement. I hope we can continue this tone in future threads. This sounds bizarre but I'm glad we still don't agree. We all learn in these forums by presenting & hearing different views - so long as they are forthright and explained. (yeah I know that sounds like insincere cheesy BS but it's not really) Part of why I kept responding was that confronting misconceptions about raid as well as exploring what "reliability" means is of benefit to the group. Another was purely selfish, as I was really hoping to force out compelling evidence that large cheap SATA raid is "proven" and ready to replace some other more expensive installations. I'm not saying this to keep contention alive. In fact you made me re-look at and reconsider product lines and a few newer products seem much more compelling than ones I saw available even a few months ago. I still think though I'm going to wait at least another product cycle or two before putting a new sata in the test lab again in plans for use and recommendation. But the day is drawing closer... I hope we haven't scared the group off continuing to discuss more detail of raid in future threads. I may have overdone it here. I bet everyone is sorry you pressed me so hard for "details" (if there is anyone still reading). |
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