hello,
I have a raid6 with 4 disks. 2 of them show Current_Pending_Sector 1.
Hi Basti
are you using mdadm for the raid-6 or a hardware raid controller?
The disks has warranty till Apr. 2019 so I decide to replace them.
If there's only 1 current pending sector it could be difficult to get a full replacement. HDD's have spare sectors which are used in such events and are (*should*) be capable to handle a few defect sectors. It doesn't mean (yet) that the drive is defect.
After I change the disk and install it on an other computer to overwrite
with zero it the Current_Pending_Sector is gone.
Yes, I've seen this too a couple of months ago on a remote NAS server. I probably had the same reaction as you: I couldn't believe it. Especially as the Current_Pending_Sector went to 0 and Reallocated_Sectors and Offline_Uncorrectable staid at the same value as before, too.
What should I do? Whats our experience?
Continuously monitor your drive's SMART values and (if possible) store the results in a database (RRD, Timeseries DB, you name it) to create graphs from the values. You can use the
check_smart.pl monitoring plugin as an examle. This will show you if the number of defect sectors increase or if they stay steady. If the bad sectors increase, it's just a matter of time until the drive physically fails. You can see an example of such a graph (rrd in this case) with increasing bad sectors over 5 weeks here:
As helpful as SMART is, never rely 100% on it, as drives may also fail without any bad values in SMART.