Justin Piszcz wrote:
I asked before but it was kind of clobbered in the velociraptor mess:
On a colleague's box:
Aug 02, 2008 12:15.30AM(0x04:0x0023): Sector repair completed: port=7,
LBA=0x4A0387F5
SMART Self-test log structure revision number 0
Warning: ATA Specification requires self-test log structure revision
number = 1
Num Test_Description Status Remaining
LifeTime(hours) LBA_of_first_error
# 1 Extended offline Completed: read failure 90% 305
1241745397
Even though this disk has a bad sector:
198 Offline_Uncorrectable 0x0030 100 100 000 Old_age
Offline - 1
The controller does not drop the drive from the array when it hits an
error, the 3ware card "takes care of it" and the user need not worry
about it, whereas with md/raid every time it hits a bad sector, it
breaks the raid and it goes degraded, is this correct? Will/can
something like what 3ware does be possible in a sw-raid based
configuration or is a HW raid card required?
Presumably all it's doing is writing that sector's contents back from
the other drive(s) in the array when the read error is detected, this is
something that software could do just as well. Drives only remap bad
sectors when they are written over, as a read failure doesn't
necessarily mean that the sector is entirely unreadable, but could be
due to environmental factors such as high temperature, vibration, etc.
Just rewriting the sector seems a bit questionable though, as if a drive
in your array is growing read errors that's not really a good thing..
Justin.
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