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SCSI disk spare sectors


 
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Special Forums Hardware Filesystems, Disks and Memory SCSI disk spare sectors
# 1  
Old 12-14-2007
SCSI disk spare sectors

Is there a way to determine the number of available spare sectors on a disk ? as it may be useful for notifying a user to take a backup of the disk before it runs into a medium error.
# 2  
Old 12-14-2007
try "df -k" and "du -sk"
# 3  
Old 12-15-2007
I don't think you can do this with du.

Du (Unix - Wikipedia, the free encyclopedia)

To look at the underlying sectors, you need a lower level utility such as fdisk

fdisk - Wikipedia, the free encyclopedia
# 4  
Old 12-15-2007
Quote:
Originally Posted by Neo
To look at the underlying sectors,...
I didn't take this literally, I inferred it meant useable disk space.
# 5  
Old 12-17-2007
I am sorry. I think I confused everyone. This is what I actually meant to say..

Usually a hard disk keeps spare sectors that are not visible to the user. Whenever the disk encounters a bad block the disk internally replaces these bad blocks from the spare sectors. This operation is completely translucent to the user. There seems to be a specific number of spare sectors on any hard disk that is used for recovering from bad blocks. But once the disk runs out of spare sectors in the process of replacing bad blocks, all future bad blocks will become medium errors (unrecoverable). If the number of available spare sectors can be found then the user can be informed much earlier that its time to backup this disk as it would soon become faulty.
# 6  
Old 12-17-2007
Quote:
Originally Posted by rednex
....the user can be informed much earlier that its time to backup this disk.
You should be backing up the disk anyway irrespective of this as this is only one of the many ways your data may become unrecoverable. Power spikes, bearing failures, buggy/malicious software, erroneous deletions etc can all trash your data.

What you are asking for is very low-level and device/manufacturer specific.
# 7  
Old 12-30-2007
Quote:
Originally Posted by rednex
Usually a hard disk keeps spare sectors that are not visible to the user. Whenever the disk encounters a bad block the disk internally replaces these bad blocks from the spare sectors. This operation is completely translucent to the user. There seems to be a specific number of spare sectors on any hard disk that is used for recovering from bad blocks. But once the disk runs out of spare sectors in the process of replacing bad blocks, all future bad blocks will become medium errors (unrecoverable). If the number of available spare sectors can be found then the user can be informed much earlier that its time to backup this disk as it would soon become faulty.
See the SourceForge project called SMART:

smartmontools Home Page (last updated $Date: 2007/10/26 21:49:03 $)

Quote:
The smartmontools package contains two utility programs (smartctl and smartd) to control and monitor storage systems using the Self-Monitoring, Analysis and Reporting Technology System (SMART) built into most modern ATA and SCSI hard disks. In many cases, these utilities will provide advanced warning of disk degradation and failure.

Smartmontools is originally derived from the Linux smartsuite package, and includes support for ATA/ATAPI-3 to -7 disks and SCSI disk and tape devices. It should run on any modern Darwin (Mac OSX), Linux, FreeBSD, NetBSD, OpenBSD, Solaris, OS/2, eComStation or Windows system. Alternatively, it can also be run from one of the bootable CDs or floppies containing smartmontools.
See also:

Monitoring Hard Disks with SMART

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