Hi, Drives with SCT ERC not supported or unset, result in potentially long error recoveries for marginal or bad sectors: upwards of 180 second recovers are suggested. The kernel's SCSI command timer default of 30 seconds, i.e. cat /sys/block/<dev>/device/timeout conspires to undermine the deep recovery of most drives now on the market. This by default misconfiguration results in problems list regulars are very well aware of. It affects all raid configurations, and even affects the non-RAID single drive use case. And it does so in a way that doesn't happen on either Windows or macOS. Basically it is linux kernel induced data loss, the drive very possibly could present the requested data upon deep recovery being permitted, but the kernel's command timer is reached before recovery completes, and obliterates any possibility of recovering that data. By default. This now seems to affect the majority of use cases. At one time 30 seconds might have been sane for a world with drives that had less than 30 second recoveries for bad sectors. But that's no longer the case. I'm wondering if anyone has floated the idea of changing the kernels default SCSI command timer? And if so, if there's a thread discussing where that was rejected upstream? Or if this exposes other liabilities that merits an alternative work around for what now amounts to a defect. Maybe it needs to be a udev rule? Perhaps ideally what we'd like to have is two timers. A timer that reports back "slowness" for a drive to complete a queued command, which could be used by e.g. scrubs to preemptively overwrite those sectors rather than wait for read errors to happen. And then a timer with a longer value would be the present timer that results in a link reset once it's reached. Thanks, -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
