Re: ad0 READ_DMA TIMEOUT errors on install of 7.0-RELEASE

Stephen Hurd wrote:

Jeremy Chadwick wrote:

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
5 Reallocated_Sector_Ct 0x0033 253 253 063 Pre-fail Always - 4

This shows you've had 4 reallocated sectors, meaning your disk does in
fact have bad blocks. In 90% of the cases out there, bad blocks
continue to "grow" over time, due to whatever reason (I remember reading
an article explaining it, but I can't for the life of me find the URL).


This is unusual now? I've always "known" that a small number of bad blocks is normal. Time to readjust my knowledge again?

I have bought disks where the value of Reallocated_Sector_Ct was not 0, at least by the time I looked at it with smartctl. Nothing bad has happened to those disks in several years (hope that's not tempting fate).

I have always assumed that what matters is when this value *changes*. If it's not changing, who cares? smartd will monitor disks and email you when certain attributes change (e.g. Pre-fail attributes like Reallocated_Sector_Ct). If it changed, it would mean that an attempt to write data had failed and that reallocation had happened.

e.g. from smartd.conf

/dev/ad4 -o on -S on -a -m root -M daily

If your Current_Pending_Sector were non-zero you'd be in trouble, I believe.

0.02, pinch of salt, not an expert, slippery when hot, long time since I read the specs, etc etc.

--Alex


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