Since purchasing 16-disk arrray NAS server 4-5 months ago, 5 disks have crashed so far. They are all WD4000YS. They're all "Raid Edition" which supposed to last longer than typical drives. It has been puzzling me until now.
It turns out that "Data Lifeguard" feature was confusing the RAID controller to believe that the disk was dead, hence the "failed" disk. AFAIK, Western Digital released firmware update on 01/09/07 that's supposed to fix this.
http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=1493&p_created=1168299631&p_sid=vfEX7qri&p_accessibility=0&p_redirect=&p_lva=&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3J vd19jbnQ9MiZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wdj0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9mbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1XRDQwMDBZUw**&p_li=&p_ topview=1
So, if you have WDxxxxYS on your pre-production server, pull them out for a firmware update first!
For me, I can only swap "hot-spare" out for a firmware update. For other disks, I'll just have to wait for them to "drop" out of the array first. I cannot take this server offline at all. Any suggestions?