Hard Drive Bad Blocks and SMART Notes

Terminology

Soft bad blocks / sectors and hard / physical bad blocks / sectors.

Sector Re-Allocation vs File System "black list"

I realized today, that once a HDD's built in bad sector re-allocation table is used up, you have to rely on the file system. So... rather than blow away the NTFS partition, you install on top of one that has already run a full chkdsk /r to find all the bad sectors. Whether it's smart to continue to use a disk with bad blocks... that's another issue.

Windows Event 7 in System Event Log Interpretation

It's annoyingly unclear which physical disk is having a "bad block", especially when multiple physical disks are installed. WinObj by SysInternals has an easy tree to drill down to DR0 or whatever (still not great, doesn't give disk serial number or anything, but does show how many partitions are on the disk)

TBC: Write to disk to detect all bad blocks

Modern Windows has cipher command which is meant to secure a drive. "cipher /W:C:" will write zeroes and then random data to all empty space on the drive, which will in effect, test all blocks for functionality - I think. Nullfile from G4U will work as well - but that's 3rd party.

Cipher actually just writes files to a temp folder... I hope it clears automatically if someone randomly restarts the computer part way.

Testing a Disk

Run "badblocks" from a Linux boot disk, e.g. Gparted Live.

Trying: badblocks -v /dev/sdb1 -e 5 -s -n -- supposed to do a FS safe write test, max 5 bad blocks before bailing, verbose output.

Reset NTFS Bad Blocks List

Hmm... I'd like to mirror a drive in Windows 2003 for a client, but the source disk has a bad block from some point in the past. The people who originally set this server up should have mirrored from day 1...

Unfortunately, Windows mirror will not mirror a drive with ANY (physical) bad blocks. http://support.microsoft.com/kb/325615

I think I need to do a disk to disk image with Knoppix, then, if I'm feeling lucky, reset the NTFS bad blocks list.

http://www.linux-ntfs.org/doku.php?id=ntfsclone#reseting_the_bad_sectors_list_after_cloning

Or, will using the manufacturers extended disk scan remap the physical bad blocks so that Windows won't see it when trying to mirror?

Update: Vista and newer have a /b switch for chkdsk to reset the bad blocks list.

SMART Read from Windows

Open Source - https://gsmartcontrol.sourceforge.io/home/

SMART Interpretation

Value: This is the raw value that the controller reports. Usually it's an easy to understand value (like power on hours or temperature), but sometimes it isn't (like the read error rate). Different manufacturers can use different structures and meanings for this data.
Normalized: This is the above value normalized so a higher value is always better. So a 114 in read/error rates is better than 113. Again, how your hard drive converts raw data to normalized value is vendor specific.
Worst: The worst normalized value that your drive had in the past (where 99 is likely the factory setting).
Threshold: When the normalized value is lower than this value the drive is likely to fail.
https://askubuntu.com/questions/20393/how-do-i-interpret-hdd-s-m-a-r-t-results

Reallocated sectors count - Indicates how many defective sectors were discovered on the drive and remapped using a spare sectors pool. Low values in absence of other fault indications point to the disk surface problem. Raw value indicates the exact number of such sectors. - http://www.z-a-recovery.com/manual/smart.aspx

tags: raid, mirror, software, w2k3, bad, blocks