On 07/27/2011 06:16 AM, NeilBrown wrote:
Then as errors occur they will cause the faulty block to be added to the log rather than the device to be remove from the array.
Can you describe the criteria for MD considering a block as faulty? In your blog, I read "... known to be bad. i.e. either a read or a write has recently failed..." but that definition may be problematic: I've experienced drives with intermittent read / write failures (due to controller or power stability problems), and I wonder whether such a situation could quickly fill up the "bad block list", doing more harm than good in the "intermittent error"- szenario. Another szenario: The write succeeded, but a later reads of the same block return read errors. This would result in a "pending sector", and the harddisk may very well re-map the sector on the next write. Do you mark the block faulty on the MD level after the first read failed (even though subsequent reads/writes to the block would succeed), or do you first try to re-write the block, and call it faulty only if that fails? One more general thing: I guess that "marking bad blocks" is probably unsuitable for SSDs, which usually do not assign fixed physical storage location with a certain block number. Maybe mdadm could warn about better not enabling the feature if the device is known to be a SSD. Regards, Lutz Vieweg -- 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
