rcfa

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Everything posted by rcfa

  1. rcfa

    IBM Deskstar 120GXP

    Surely is much faster, if the electronics can keep up. Theoretically you could even do parallel reads off the various platters, and then achieve similar performance gains as in RAID arrays in comparison to reading only one platter's data at a time. A striping RAID reads multiple drives at once, so it's the same thing, just one step up the abstraction hierarchy. Data rates depend on bit density, rotational speed. If you then read N platters concurrently, with other parameters the same and no interface bottlenecks, you Ntuple the data rate.
  2. rcfa

    IBM Deskstar 120GXP

    Well, I discovered that early on, and my suspicion is that it might have something to do with the fluid bearing, viscosity breakdown, or something like that... Anyway, I asked IBM, and here the result of that exchange: (I cut my e-mail address and the name of the IBM rep, because I don't want to get him fired if he disclosed more than he was supposed to...) Me, myself and I: I have an IDE-to-SCSI RAID which takes 6 EIDE HDs, creates a RAID-5 array from them, and presents the resulting storage to the host computer as if it were a single, large SCSI drive. Currently this array is loaded with 6 IBM 34GXP 34 GB Deskstar drives, however I want to increase the capacity, and was thinking of replacing these drives with 6 of the 120GXP Deskstar drives. The recent troubles with the 60GXP series drives made me wonder about potential reliability problems. Then I read the technical specs of the 120 GXP series, and there I find the following item, notably under the title "Reliability": "Recommended power-on hours (monthly) 333" Does this mean this drive is not a reliable choice to be used in a RAID that's running 24*7 ? I cannot find similar exclusions on either Maxtors or WesternDigital's drive specs, and the later specifies a non-recoverable error rate that's an order of magnitude better, and claims a minimum of 50k start/stop cycles, while the IBM drive claims an average of 40k start/stop cycles. Are IBM's specs just particularly conservative in their estimates or is the side effect of the drive being more silent and marginally faster than the WD1200JB, that the reliability suffers and that it loses the ability to be used in a 24*7 set up? What about all the people who'd like to use a big drive like this in various slimline rackmount internet servers? Will they have to go elsewhere? IBM: No IBM ATA drive has been rated for use in a 24/7 environment. In most cases, only SCSI drives are rated for this type of usage. ATA RAID is a relatively new market. It may work, but it is not tested by IBM in this capacity. Me, myself and I: thanks a lot for your answer. I would strongly suggest that IBM rethinks their strategy, however. While ATA RAIDs are relatively new (at least in terms of common visibility, they have been on the market for at least four years now), rackmount LINUX servers are not. There must be thousands, if not millions of 1U or2U PC based rackmount Linux servers in server farms that are rented out to people who want to host their own web site or e-store at a managed site. This was even acknowledged in the product description of your new 60GB TravelStar drive, which is now rated for "continuous use" in "blade servers". Similarly many offices that just need a workgroup e-mail and intranet server for low data volume applications commonly use a desktop PC, often even one that's no longer a current model, because serving a few intranet web pages is a low CPU power job, so even a relatively outdated machine can take care of this. Hardly anyone uses SCSI drives in such circumstances, particularly since Microsoft software makes it a pain to deal with SCSI, while ATA is comparatively speaking a breeze. IBM: This is not something that we can change. This is a barrier that is part of the IDE infrastructure There is no way for us, nor any other manufacturer, to overcome this. This is now, and probably will be for quite some time, the primary difference between IDE and SCSI. The Travelstar 60GB seems to be an exception to the rule. How this was accomplished I do not know. Me, Myself and I: with all due respect, but I don't understand your answer. I don't see how an electrical interface specification and data transfer protocol (EIDE/ATA) has any influence on the reliability of the drive, which is largely a matter of mechanics, read/write heads, electronics, lubrication, etc. The fact that one drive uses and EIDE/ATA interface doesn't make it necessary that it can only endure 333h power-on per month, while a SCSI drive can work in a 24*7 environment. That SCSI drives may be faster due to the built-in smarts, etc. is a completely different story. What seems to be much more believable is that in order to be able to compete on price, which is key in the desktop market, not the same amount of quality engineering goes into the mechanics and electronics of the EIDE/ATA drives that goes into the more expensive SCSI drives. The fact that the TravelStar 60GB drive can withstand a 24*7 operational environment shows only that on a drive like this the margins are fat enough to put the relevant quality into the mechanism. Several other manufacturers advertise their higher-capacity EIDE/ATA drives for use in work group servers (which run 24*7) or for the use in rack-mount internet appliances (which also run 24*7). So either IBM is more cautious, or their quality is better. Needless to say, without access to data proprietary to each of these companies, there is no way of telling which is the case. Now should I have missed a point as to *why* EIDE/ATA drives cannot be built as reliable as SCSI drives, I'd sure like to know. IBM: *Silence* Me, Myself and I: I think I'll have to go with a WD drive, because I can't gamble with my server's reliability, and so access speed will have to take second priority. After all, the WD1200JB is no slouch either. Ronald