On 08/27/2009 05:22 PM, Andrei Tanas wrote:
Hello, This is about the same problem that I wrote two days ago (md gets an error while writing superblock and fails a hard drive). I've tried to figure out what's really going on, and as far as I can tell, the disk doesn't really fail (as confirmed by multiple tests), it times out trying to execute ATA_CMD_FLUSH_EXT ("at2.00 cmd ea..." in the log) command. The reason for this I believe is that md_super_write queues the write comand with BIO_RW_SYNCIO flag. As I wrote before, with 32MB cache it is conceivable that it will take the drive longer than 30 seconds (defined by SD_TIMEOUT in scsi/sd.h) to flush its buffers. Changing safe_mode_delay to more conservative 2 seconds should definitely help, but is it really necessary to write the superblock synchronously when array changes status from active to active-idle? [90307.328266] ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [90307.328275] ata2.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 [90307.328277] res 40/00:01:01:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) [90307.328280] ata2.00: status: { DRDY } [90307.328288] ata2: hard resetting link [90313.218511] ata2: link is slow to respond, please be patient (ready=0) [90317.377711] ata2: SRST failed (errno=-16) [90317.377720] ata2: hard resetting link [90318.251720] ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [90318.338026] ata2.00: configured for UDMA/133 [90318.338062] ata2: EH complete [90318.370625] end_request: I/O error, dev sdb, sector 1953519935 [90318.370632] md: super_written gets error=-5, uptodate=0
30 seconds is a very long time for a drive to respond, but I think that your explanation fits the facts pretty well...
The drive might take a longer time like this when doing error handling (sector remapping, etc), but then I would expect to see your remapped sector count grow.
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