Messages in this thread | | | Date | Sat, 6 Dec 2008 07:11:32 -0500 (EST) | From | Justin Piszcz <> | Subject | Re: Have the velociraptors in a test system now, checkout the errors. |
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On Sat, 6 Dec 2008, Michael Tokarev wrote:
> Justin Piszcz wrote: >> Point of thread: Two problems, mentioned in detail below, NCQ in Linux > [] > >> Two-disks failed out of the RAID5 and I currentlty cannot even 'see' one >> of the drives with smartctl, will reboot the host and check sde again. > > Not to say it's your case (i remember you mentioned a new powerful PSU > in your last emails), but anyway. > > We had numerous, countless disk failures like this in the past - with > seagate scsi drives (not sas, not sata but ol'good scsi - 9Gb and 36Gb > barracuda ones). As that - a drive suddenly disappears from the bus, > without any indication it was/is here, only power-cycle cures the prob. > > One such case were related to a broken (it seems) batch of those 9Gb > drives (it was back in 2000 or so). The frequency of such failures > fluctuated a lot, and did not depend on system load - it was possible > to see disk disappearance after a few mins after boot without any load, > or it may run for several weeks under a good load. The failing drive > was always the same, replace it and voila, it works again. There was > about 10..20 such drives we had, some are still here somewhere (not in > use). > > And another case was with 36gb 10krpm barracudas, at about 2004 or so. > And also with 18gb 15Krpm maxtors. Some of them. > > This case looked really mysterious to me. Until I found (after many > many times experimenting with all that) that the cause is under-powered > PSU. For example, when there were 2 disks running on the system, no > hdd stopped, but with 4 disks rinning, one were quite likely to stop > (always the same, other disks were working still). When this new > problem started appearing and I had not yet understand the cause, > we also tried to replace the "failing" drives, and it helped somewhat, -- > i.e., there were high chances that the replacement disk will actually > work better. But some non-zero chance existed that it will not work > the same or even worse way the "failing" drive failed. > > It come to good surprize to me that the problem was the PSU. It was > 350W (quite descent in 2002 when the test system was bought), but > obviously not enough for the load with all the 15krpm drives... > (and later on the system become instable too, and now I know why - > also lack of proper power, now for chipset/cpu). > > The prob with 9gb drives were real (not due to the PSU), but > Seagate never acknowleged it. > > Just... another "funny" scenario which happened for real. > And my probs obviously were NOT related to NCQ (TCQ really) - > TCQ worked on all those drives just fine, much better and > with much better effect than all thouse modern NCQ-aware > drives..... Ohwell. > > /mjt >
Very interesting story there, what OS(') were you using at the time? Windows? Linux? UNIX?
As far the PSU, just btw/FYI, Velociraptors consume ~4-5 watts a piece, my entire system used ~100-120watts with all 12 velociraptors on a 650 watt PSU (now moved into a test system).
Justin.
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