Hi William,
My comment was just a heads up so other developer’s don’t get take a hit like I did. Just look at your disk SMART data and you will be surprised by the number of errors on those disks. Here is an example of SMART info from one of my 4TB WD disks I use with TimeMachine. As you can see, 0 errors in the log. On my development system, I use 1TB Seagate SSD drives and they work great.
Last Checked : November 29, 2015 2:25:14 PM PST
Last Checked (ISO 8601 format) : 2015-11-29T14:25:14
Advanced SMART Status : OK
Overall Health Rating : GOOD 89.9%
Overall Performance Rating : GOOD 89.9%
Issues found : 0
Serial Number : WD-WCC4E0HHFLY1
WWN Id : 5 0014ee 260fbf0bd
Volumes : TimeMachine1
Device Path : /dev/disk4
Total Capacity : 4.0 TB (4,000,787,030,016 Bytes)
Model Family : Western Digital Red
Model : WDC WD40EFRX-68WT0N0
Firmware Version : 82.00A82
Drive Type : HDD 5400 rpm
Power On Time : 5,078 hours (7 months 1 days 14 hours)
Power Cycles Count : 54
Current Power Cycle Time : 22.1 hours
=== DEVICE CAPABILITIES ===
S.M.A.R.T. support enabled : yes
DriveDx Active Diagnostic Config : Base config [hdd.default]
Sector Logical Size : 512
Sector Physical Size : 4096
Physical Interconnect : SATA
Removable : no
Ejectable : no
ATA Version : ACS-2 (minor revision not indicated)
SATA Version : SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Bay # : 1
I/O Path : IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/PEG1@1,1/IOPP/UPSB@0/IOPP/DSB2@4/IOPP/UPS0@0/IOPP/pci-bridge@3/IOPP/pci1b21,612@0/AppleAHCI/PRT0@0/IOAHCIDevice@0/AppleAHCIDiskDriver/IOAHCIBlockStorageDevice
Attributes Data Structure Revision : 16
SMART Command Transport (SCT) flags : 0x703d
SCT Status supported : yes
SCT Feature Control supported : yes
SCT Data Table supported : yes
Error logging capabilities : 0x1
Self-tests supported : yes
Offline Data Collection capabilities : 0x7b
Offline Data Collection status : 0x0
Auto Offline Data Collection flags : 0x0
[Known device ]: yes
[Drive State Flags ]: 0x0
=== CURRENT POWER CYCLE STATISTICS ===
Data Read : 2.2 GB
Data Written : 3.5 GB
Data Read/Write Ratio : 0.62
Average Throughput (Read) : 1.2 MB/s
Average Throughput (Write) : 932.4 KB/s
Operations (Read) : 175,372
Operations (Write) : 153,554
Operations Read/Write Ratio : 1
Throughput per operation (Read) : 12.9 KB/Op
Throughput per operation (Write) : 23.6 KB/Op
Latency Time (Read) : 0 ns
Latency Time (Write) : 0 ns
Retries (Read) : 0
Retries (Write) : 0
Errors (Read) : 0
Errors (Write) : 0
=== PROBLEMS SUMMARY ===
Failed Indicators (life-span / pre-fail) : 0 (0 / 0)
Failing Indicators (life-span / pre-fail) : 0 (0 / 0)
Warnings (life-span / pre-fail) : 0 (0 / 0)
Recently failed Self-tests (Short / Full) : 0 (0 / 0)
I/O Errors Count : 0 (0 / 0)
Time in Under temperature : 0 minutes
Time in Over temperature : 0 minutes
=== IMPORTANT HEALTH INDICATORS ===
ID NAME RAW VALUE STATUS
5 Reallocated Sector Count 0 100% OK
197 Current Pending Sectors Count 0 100% OK
198 Offline Uncorrectable Sector Count 0 100% OK
199 UDMA CRC Error Count 0 100% OK
=== TEMPERATURE INFORMATION (CELSIUS) ===
Current Temperature : 33
Power Cycle Min Temperature : 27
Power Cycle Max Temperature : 37
Lifetime Min Temperature : 23
Lifetime Max Temperature : 49
Recommended Min Temperature : 0
Recommended Max Temperature : 60
Temperature Min Limit : -41
Temperature Max Limit : 85
=== DRIVE HEALTH INDICATORS ===
ID | NAME | TYPE | UPDATE | RAW VALUE | VALUE | THRESHOLD | WORST | STATUS | LAST MODIFIED
1 Raw Read Error Rate Pre-fail online 0x0 200 51 200 100% OK 5/13/15 8:43 PM
3 Spin Up Time Pre-fail online 7,891 182 21 177 89.9% OK 11/29/15 2:25 PM
4 Start Stop Count Life-span online 4,129 96 0 96 96.0% OK 11/29/15 2:25 PM
5 Reallocated Sector Count Pre-fail online 0 200 140 200 100% OK -
7 Seek Error Rate Life-span online 0x0 200 0 200 100% OK -
9 Power On Hours Life-span online 5,078 94 0 94 94.0% OK 11/29/15 2:25 PM
10 Spin Retry Count Life-span online 0 100 0 100 100% OK -
11 Calibration Retry Count Life-span online 0 100 0 253 100% OK -
12 Power Cycle Count Life-span online 54 100 0 100 100% OK 11/28/15 4:19 PM
192 Power-Off Retract Count Life-span online 21 200 0 200 100% OK 11/12/15 2:02 PM
193 Load Cycle Count Life-span online 9,125 197 0 197 98.5% OK 11/29/15 2:25 PM
194 Temperature (Celsius) Life-span online 33 119 0 103 99.2% OK 11/29/15 2:25 PM
196 Reallocated Event Count Life-span online 0 200 0 200 100% OK -
197 Current Pending Sectors Count Life-span online 0 200 0 200 100% OK -
198 Offline Uncorrectable Sector Count Life-span offline 0 100 0 253 100% OK -
199 UDMA CRC Error Count Life-span online 0 200 0 200 100% OK -
200 Multi Zone Error Rate Life-span offline 0 100 0 253 100% OK -
=== DRIVE ERROR LOG ===
error log is empty
=== DRIVE SELF-TEST LOG ===
self-test log is empty
Regards,
John