Help with drive failure

Library:/# cat /var/log/frontview/enclosure.log 
temp!!1!!status=ok::descr=36.0C/96.8F::expected=0-60C/32-140F
fan!!1!!status=ok::descr=2343RPM
ups!!1!!status=not_present::descr=Not present
volume!!1!!status=warn::descr=Volume C: RAID Level 5, Not redundant.  A disk failure will render this volume dead.; 822 GB (75%) of 1088 GB used
disk!!1!!status=ok::descr=Channel 1: SAMSUNG HD501LJ 465 GB, 38C/100F
disk!!2!!status=not_present::descr=Not present
disk!!3!!status=ok::descr=Channel 3: Seagate ST3400832AS 372 GB, 50C/122F
disk!!4!!status=ok::descr=Channel 4: Seagate ST3400832AS 372 GB, 47C/116F
model!!0!!mode=pro::descr=ReadyNAS NV::arch=nsp
Library:/# tail /var/log/frontview/status.log-old 
1!!Sat Dec 31 20:15:44 EST 2011!!root!!Please close this browser session and use RAIDar to reconnect to the device.  System rebooting...
0!!Sat Dec 31 20:15:44 EST 2011!!root!!Rebooting device...
0!!Sat Dec 31 20:18:25 EST 2011!!root!!System is up.
1!!Sat Dec 31 23:21:40 EST 2011!!root!!The iTunesServer add-on has been successfully installed.
1!!Sat Dec 31 23:21:36 EST 2011!!root!!Successfully installed iTunes Streaming Server 1.0.3 update.
1!!Sat Dec 31 23:24:16 EST 2011!!root!!Successfully stopped Firefly (iTunes) Media Server.
1!!Sat Dec 31 23:24:30 EST 2011!!root!!Successfully started Firefly (iTunes) Media Server.
1!!Sun Jan  1 10:46:38 EST 2012!!root!!Please close this browser session and use RAIDar to reconnect to the device.  System rebooting...
0!!Sun Jan  1 10:46:39 EST 2012!!root!!Rebooting device...
0!!Sun Jan  1 10:49:48 EST 2012!!root!!System is up.
Library:/# tail /var/log/frontview/status.log-new 
2!!Thu Oct 18 04:00:04 EDT 2012!!root!!ATA error count has increased in the last day.\n\nDisk  1:\n  Previous count: 725\n  Current count: 736\n\nGrowing SMART errors indicate a disk that may fail soon.  If the errors continue to increase, you should be prepared to replace the disk.
3!!Fri Oct 19 00:09:01 EDT 2012!!root!!Error encountered copying data from source path  ==> /USB_HDD_1/ due to lack of disk space. [Job 001]
2!!Fri Oct 19 04:00:04 EDT 2012!!root!!ATA error count has increased in the last day.\n\nDisk  1:\n  Previous count: 736\n  Current count: 748\n\nGrowing SMART errors indicate a disk that may fail soon.  If the errors continue to increase, you should be prepared to replace the disk.
1!!Fri Oct 19 04:19:15 EDT 2012!!root!!Please reboot your ReadyNAS device to continue with the update process.
3!!Mon Oct 22 00:08:46 EDT 2012!!root!!Error encountered copying data from source path  ==> /USB_HDD_1/ due to lack of disk space. [Job 001]
2!!Mon Oct 22 04:00:04 EDT 2012!!root!!ATA error count has increased in the last day.\n\nDisk  1:\n  Previous count: 748\n  Current count: 760\n\nGrowing SMART errors indicate a disk that may fail soon.  If the errors continue to increase, you should be prepared to replace the disk.
1!!Mon Oct 22 06:57:26 EDT 2012!!root!!Please reboot your ReadyNAS device to continue with the update process.
3!!Tue Oct 23 00:09:11 EDT 2012!!root!!Error encountered copying data from source path  ==> /USB_HDD_1/ due to lack of disk space. [Job 001]
2!!Tue Oct 23 04:00:04 EDT 2012!!root!!ATA error count has increased in the last day.\n\nDisk  1:\n  Previous count: 760\n  Current count: 771\n\nGrowing SMART errors indicate a disk that may fail soon.  If the errors continue to increase, you should be prepared to replace the disk.
3!!Wed Oct 24 00:10:35 EDT 2012!!root!!Error encountered copying data from source path  ==> /USB_HDD_1/ due to lack of disk space. [Job 001]
Library:/# cat /var/log/frontview/memory.log 
SZ: 256
AT: 2.0-2-2-6
ID: 7f7f7f7f7f020000
PN: 000000000000000000000000000000000000
RV: 0000
DT: 0000
SN: 00000000

Library:/#