Disk Fail Event During Duo Expansion

can you post smartctl.log here?you can download logs in Frontview-->status-->logs>download all logs.

de niro - here is the smartctl.log. Thanks for the post.

***** smartctl output for hdc *****

smartctl 5.42 2011-10-20 r3458 [padre-linux-2.6.17.14ReadyNAS] (local build)
Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net

=== START OF INFORMATION SECTION ===
Model Family: Seagate DB35.3
Device Model: ST3500830SCE
Serial Number: 5QG2N83X
Firmware Version: 3.ACD
User Capacity: 500,107,862,016 bytes [500 GB]
Sector Size: 512 bytes logical/physical
Device is: In smartctl database [for details use: -P show]
ATA Version is: 7
ATA Standard is: Exact ATA specification draft version not indicated
Local Time is: Sun May 19 16:18:04 2013 EDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status: (0x82) Offline data collection activity
was completed without error.
Auto Offline Data Collection: Enabled.
Self-test execution status: ( 0) The previous self-test routine completed
without error or no self-test has ever
been run.
Total time to complete Offline
data collection: (15556) seconds.
Offline data collection
capabilities: (0x5b) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
command.
Offline surface scan supported.
Self-test supported.
No Conveyance Self-test supported.
Selective Self-test supported.
SMART capabilities: (0x0003) Saves SMART data before entering
power-saving mode.
Supports SMART auto save timer.
Error logging capability: (0x01) Error logging supported.
General Purpose Logging supported.
Short self-test routine
recommended polling time: ( 1) minutes.
Extended self-test routine
recommended polling time: ( 163) minutes.

SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x000f 101 099 006 Pre-fail Always - 3259337
3 Spin_Up_Time 0x0003 092 091 000 Pre-fail Always - 0
4 Start_Stop_Count 0x0032 100 100 020 Old_age Always - 819
5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 0
7 Seek_Error_Rate 0x000f 073 060 030 Pre-fail Always - 24133732
9 Power_On_Hours 0x0032 065 065 000 Old_age Always - 31133
10 Spin_Retry_Count 0x0013 100 100 097 Pre-fail Always - 0
12 Power_Cycle_Count 0x0032 100 100 020 Old_age Always - 23
187 Reported_Uncorrect 0x0032 100 100 000 Old_age Always - 0
189 High_Fly_Writes 0x003a 100 100 000 Old_age Always - 0
190 Airflow_Temperature_Cel 0x0022 059 049 045 Old_age Always - 41 (Min/Max 32/43)
194 Temperature_Celsius 0x0022 041 051 000 Old_age Always - 41 (0 23 0 0 0)
195 Hardware_ECC_Recovered 0x001a 062 052 000 Old_age Always - 228212426
197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0010 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x003e 200 200 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x0000 100 253 000 Old_age Offline - 0
202 Data_Address_Mark_Errs 0x0032 100 253 000 Old_age Always - 0

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1

SMART Selective self-test log data structure revision number 1
SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS
1 0 0 Not_testing
2 0 0 Not_testing
3 0 0 Not_testing
4 0 0 Not_testing
5 0 0 Not_testing
Selective self-test flags (0x0):
After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.





***** smartctl output for hde *****

smartctl 5.42 2011-10-20 r3458 [padre-linux-2.6.17.14ReadyNAS] (local build)
Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net

Smartctl: Device Read Identity Failed: empty IDENTIFY data

A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.

Drive 2 is not recognized correctly which could be a dead drive,you need to plug this drive onto computer to check its condition and move drive 1 to slot 2 to make sure the SATA controller is fine

I'm getting to think you are right. I took a full backup then put the new 1 TB drive by itself in slot 1. The NAS came up fine. I powered down and re-installed the old 500 GB drive in slot 1 - came up fine - then re-installed 1 TB drive in slot 2. The 1 TB drive initialized and got to over 50% complete with synchronization when another SATA re-set occurred - BUMMER. I'm going to buy another 1 TB drive (which I needed to do anyway to get to X-Raid capability) and see if I have either a disk problem or a NAS problem. I'll let you know next weekend.