Re: [gentoo-user] recovery from /var corruption?

[Mark Knecht]

On Fri, Feb 26, 2010 at 1:46 AM, Alex Schuster <wonko@×××××××××.org> wrote:
> Mark Knecht writes:
>
>> Do I just watch the logs looking for problems? I have no way of
>> knowing right now whether this was a disk problem that's going to come
>> back, a 1 time deal due to power, or something else entirely.
>>
>> As these cheap machines that don't use RAID what's the right way to
>> go? emerge -e @world and then wait for the next event? Do nothing and
>> wait?
>
> Emerge smartmontools, then:
>
> smartctl -h /dev/sda  # get overview of what the drive thinks about itself
>
> smartctl -t short /dev/sda     # start short self test
> Wait
> smartctl -l selftest /dev/sda  # see results
>
> smartctl -t long /dev/sda      # start long self test
> Wait a lot longer
> smartctl -l selftest /dev/sda  # see results
>
> You can continue working in the meanwhile, there will be no performance
> impact. You will see something like this in the log:
>
> === START OF READ SMART DATA SECTION ===
> SMART Self-test log structure revision number 1
> Num  Test_Description   Status              Remaining  LifeTime(hours)
> LBA_of_first_error
> # 1  Short offline      Completed without error   00%    2275       -
> # 2  Extended offline   Completed without error   00%    2270       -
> # 3  Extended offline   Completed without error   00%    1799       -
> # 4  Extended offline   Completed without error   00%     197       -
> # 5  Extended offline   Completed without error   00%      26       -
>
> I you have a '-' in the right column, the disk has found no errors. If
> there is a number, than it's the position of the first error.
>
> There's also badblocks, this will check every block and output the bad
> ones: badblocks -sv /dev/sda
>
> badblocks -svn /dev/sda will do a read-write test. In case of a bad block,
> the drive should exchange it with a spare one. Maybe this happens already
> in read-only mode, I am not sure.
>
> Also watch for errors in syslog or via dmesg, there should be some when
> bad blocks are being accessed.
>
>        Wonko
>
>

Hi Wonko,
   Yes, I do use smartctl on some other machines although I'm not very
good about it and your write-up is helpful so thanks for that.

   My wife's machines is older and and I don't think SMART is
supported on her drive. Note the lack of a * on the SMART line in
hdparm -I:

dragonfly ~ # hdparm -I /dev/hda

/dev/hda:

ATA device, with non-removable media
	Model Number:       WDC WD1600BB-00FTA0
	Serial Number:      WD-WMAES2091586
	Firmware Revision:  15.05R15
Standards:
	Supported: 6 5 4
	Likely used: 6
Configuration:
	Logical		max	current
	cylinders	16383	16383
	heads		16	16
	sectors/track	63	63
	--
	CHS current addressable sectors:   16514064
	LBA    user addressable sectors:  268435455
	LBA48  user addressable sectors:  312581808
	Logical/Physical Sector size:           512 bytes
	device size with M = 1024*1024:      152627 MBytes
	device size with M = 1000*1000:      160041 MBytes (160 GB)
	cache/buffer size  = 2048 KBytes (type=DualPortCache)
Capabilities:
	LBA, IORDY(can be disabled)
	Standby timer values: spec'd by Standard, with device specific minimum
	R/W multiple sector transfer: Max = 16	Current = 16
	Recommended acoustic management value: 128, current value: 254
	DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5
	     Cycle time: min=120ns recommended=120ns
	PIO: pio0 pio1 pio2 pio3 pio4
	     Cycle time: no flow control=120ns  IORDY flow control=120ns
Commands/features:
	Enabled	Supported:
	    	SMART feature set
	    	Security Mode feature set
	   *	Power Management feature set
	   *	Write cache
	   *	Look-ahead
	   *	Host Protected Area feature set
	   *	WRITE_BUFFER command
	   *	READ_BUFFER command
	   *	DOWNLOAD_MICROCODE
	    	SET_MAX security extension
	    	Automatic Acoustic Management feature set
	   *	48-bit Address feature set
	   *	Device Configuration Overlay feature set
	   *	Mandatory FLUSH_CACHE
	   *	FLUSH_CACHE_EXT
	   *	SMART error logging
	   *	SMART self-test
Security:
		supported
	not	enabled
	not	locked
	not	frozen
	not	expired: security count
	not	supported: enhanced erase
HW reset results:
	CBLID- above Vih
	Device num = 0 determined by CSEL
Checksum: correct
dragonfly ~ #

dragonfly ~ # smartctl -H /dev/hda
smartctl version 5.38 [i686-pc-linux-gnu] Copyright (C) 2002-8 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

SMART Disabled. Use option -s with argument 'on' to enable it.
dragonfly ~ # smartctl -s on /dev/hda
smartctl version 5.38 [i686-pc-linux-gnu] Copyright (C) 2002-8 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

=== START OF ENABLE/DISABLE COMMANDS SECTION ===
Error SMART Enable failed: Input/output error
Smartctl: SMART Enable Failed.

A mandatory SMART command failed: exiting. To continue, add one or
more '-T permissive' options.
dragonfly ~ #

I've not tried the -T permissive options.

I've never used badblocks as it seems I should only do that off-line.
This might be a good time to boot with a CD and try it out.

Maybe I should just get a new drive that supports SMART?

- Mark