Reallocated Sector Count - Best Practices

jlehtinen wrote:
I've got a set of 6 Seagate ST3500514NS 500GB - each drive seems to pick up an additional reallocated sector every week or two. Some of them are up to around ~30 reallocated sectors at this point. What is "normal" growth you have seen for reallocated sectors?

Answer is clear, 0 reallocated sectors, is "normal".
There isnt such thing as normal growth of reallocated sectors, its a faulty drive if it starts to reallocating.
Basically its ticking "timebomb", there isnt enough spare sectors to reallocate whole drive, on one day "boom" and youre data is just gone...

jlehtinen wrote:
What is the best practice for replacing drives due to reallocated sector count? At what number of reallocated sectors should I start worrying?

Actually you should start worrrying, after it starts rising, 1 is not a big deal, untill if it incriments, there is definately something wrong with your drive and you should back up your data and replace it.

jlehtinen wrote:
Interesting side note - in the same ReadyNAS, I have 6 WDC WD1002FBYS-02A6B0 1TB drives. These drives have yet to pick up a single reallocated sector, and have been running for the same time, and under the same load as the Seagate drives. Difference in quality maybe?

Different Manufacturer, slightly different materials and process...dropped on transport to store...etc...
(We once got whole box, 20 x 4TB Hitachi drives all DOA, so..)