On Sunday 23 June 2013, Pavel Machek wrote: > 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 Being tired of using hdparm manually, I created a simple hdd_realloc utility that reads the disk in big blocks (1 MB). When there's a read error, it reads the failed block sector-by-sector and tries to rewrite the sectors that fail to read. It work fine for disks with just a couple of pending sectors. #define _GNU_SOURCE #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <time.h> #include <unistd.h> #define BLOCK_SIZE 1048576 #define SECTOR_SIZE 512 int main(int argc, char *argv[]) { if (argc < 2) { fprintf(stderr, "Usage: %s <device> [pos]\n", argv[0]); return 1; } int dev = open(argv[1], O_RDWR | O_DIRECT | O_SYNC); if (dev < 1) { perror("Unable to open device"); return 2; } posix_fadvise(dev, 0, 0, POSIX_FADV_RANDOM); off64_t startpos = 0, pos = 0; if (argc > 2) { sscanf(argv[2], "%lld", &startpos); } pos = startpos; char *buf = valloc(BLOCK_SIZE); char *zeros = valloc(SECTOR_SIZE); if (!buf || !zeros) { fprintf(stderr, "Memory allocation error\n"); return 2; } memset(zeros, 0, SECTOR_SIZE); time_t starttime = time(NULL); while (1) { printf("\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b"); printf("Position: %lld B (%lld MiB, %lld GiB, sector %lld), rate %lld MiB/s", pos, pos / 1024 / 1024, pos / 1024 / 1024 / 1024, pos / SECTOR_SIZE, (pos - startpos) / 1024 / 1024 / ((time(NULL) - starttime) ? (time(NULL) - starttime) : 1) ); lseek64(dev, pos, SEEK_SET); int count = read(dev, buf, BLOCK_SIZE); if (count == 0) {/* EOF */ printf("End of disk\n"); break; } if (count < 0) { /* read error */ printf("\n"); perror("Read error"); printf("Examining %lld\n", pos); for (int i = 0; i < BLOCK_SIZE/SECTOR_SIZE; i++) { lseek64(dev, pos, SEEK_SET); if (read(dev, buf, SECTOR_SIZE) < SECTOR_SIZE) { printf("Unable to read at %lld, rewriting...", pos); lseek64(dev, pos, SEEK_SET); int result = write(dev, zeros, SECTOR_SIZE); if (result < 0) { printf("write error\n"); } else { lseek64(dev, pos, SEEK_SET); if (read(dev, buf, SECTOR_SIZE) < SECTOR_SIZE) printf("read error after rewrite\n"); else printf("OK\n"); } } pos += SECTOR_SIZE; } } else /* no error */ pos += count; } return 0; } -- Ondrej Zary -- 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
