On Sun 2013-06-23 17:27:52, Mark Lord wrote: > On 13-06-23 03:00 PM, Pavel Machek wrote: > > > > Thanks for the hint. (Insert rant about hdparm documentation > > explaining that it is bad idea, but not telling me _why_ is it bad > > idea. Can I expect cache consistency issues after that, or is it just > > simple "you are writing to the disk without any checks"? Plus, I guess > > documentation should mention what sector number is. I guess sectors > > are 512bytes for the old drives, but is it 512 or 4096 for new > > drives?) > > For ATA, use the "logical sector size". > For all existing drives out there, that's a 512 byte unit. I guessed so. (It would be good to actually document it, as well as documenting exactly why it is dangerous. Is it okay to send patches?) > > ...but it does not do the trick :-(. It behaves strangely as if it was > > still cached somewhere. Do I need to turn off the write back cache? > > No, it works just fine. You probably have more than one bad sector. > After you see a read failure, run "smartctl -a" and look at the error > logs to see what sector the drive is choking on. Well, I definitely have more than one bad sector, but I did try to read exactly the same sector and it failed. See below. root@amd:~# hdparm --yes-i-know-what-i-am-doing --read-sector 961237188 /dev/sda | uniq /dev/sda: FAILED: Input/output error reading sector 961237188: root@amd:~# hdparm --yes-i-know-what-i-am-doing --write-sector 961237188 /dev/sda /dev/sda: re-writing sector 961237188: succeeded root@amd:~# hdparm --yes-i-know-what-i-am-doing --read-sector 961237188 /dev/sda | uniq /dev/sda: FAILED: Input/output error reading sector 961237188: root@amd:~# hdparm --yes-i-know-what-i-am-doing --write-sector 961237188 /dev/sda /dev/sda: re-writing sector 961237188: succeeded root@amd:~# hdparm --yes-i-know-what-i-am-doing --read-sector 961237188 /dev/sda | uniq /dev/sda: reading sector 961237188: succeeded 0000 0000 0000 0000 0000 0000 0000 0000 root@amd:~# dd if=/dev/sda4 of=/dev/zero bs=4096 skip=$[8958947328/4096] dd: reading `/dev/sda4': Input/output error 102+0 records in 102+0 records out 417792 bytes (418 kB) copied, 6.12536 s, 68.2 kB/s root@amd:~# hdparm --yes-i-know-what-i-am-doing --read-sector 961237188 /dev/sda | uniq /dev/sda: reading sector 961237188: succeeded 0000 0000 0000 0000 0000 0000 0000 0000 root@amd:~# hdparm --yes-i-know-what-i-am-doing --read-sector 961237188 /dev/sda | uniq /dev/sda: reading sector 961237188: succeeded 0000 0000 0000 0000 0000 0000 0000 0000 root@amd:~# hdparm --yes-i-know-what-i-am-doing --read-sector 961237188 /dev/sda | uniq /dev/sda: FAILED: Input/output error reading sector 961237188: root@amd:~# > Or just low-level format it all with "hdparm --security-erase". I'd like to understand what is going on there. I can mark the blocks as bad at ext3 level, but I'd really like to understand what is going on there, and if it is hw issue, sata issue or block layer issue. (Plus, given that remapping does not work, I'd be afraid that it will kill the disk for good). The disk is root@amd:~# smartctl -a /dev/sda smartctl 5.40 2010-07-12 r3124 [i686-pc-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net === START OF INFORMATION SECTION === Model Family: Seagate Momentus 5400.6 series Device Model: ST9500325AS Serial Number: 5VE41HDA Firmware Version: 0001SDM1 User Capacity: 500,107,862,016 bytes Device is: In smartctl database [for details use: -P show] ATA Version is: 8 ATA Standard is: ATA-8-ACS revision 4 Local Time is: Sun Jun 23 23:49:15 2013 CEST SMART support is: Available - device has SMART capability. SMART support is: Enabled Thanks for support, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
