Over the past year, we’ve been releasing hard drive reliability statistics based on the drives we use to store customer data for our online backup business. As of the end of Q1 2015, we had 44,252 hard drives spinning in our data center. If we subtract boot drives and drive models with less than 45 drives from that total, we get 42,749 hard drives remaining, spread across 21 drive models. Below are the hard drive reliability statistics for these drives for Q1 2015.
| Backblaze Hard Drive Failure Rates January 1 – March 31, 2015 | |||||
|---|---|---|---|---|---|
| Name/Model | Size | Number of Drives |
Average Age in years |
Annual Failure Rate |
95% Confidence Interval |
| HGST Deskstar 7K2000 (HDS722020ALA330) |
2TB | 4,664 | 4.1 | 1.66% | 1.0% – 2.6% |
| HGST Deskstar 5K3000 (HDS5C3030ALA630) |
3TB | 4,596 | 2.9 | 0.79% | 0.4% – 1.5% |
| HGST Deskstar 7K3000 (HDS723030ALA640) |
3TB | 1,013 | 3.3 | 2.00% | 0.6% – 4.7% |
| HGST Deskstar 5K4000 (HDS5C4040ALE630) |
4TB | 2,653 | 2.0 | 1.07% | 0.4% – 2.2% |
| HGST Megascale 4000 (HGST HMS5C4040ALE640) |
4TB | 7,026 | 0.7 | 0.80% | 0.4% – 1.4% |
| HGST Megascale 4000.B (HGST HMS5C4040BLE640) |
4TB | 3,100 | 0.9 | 0.39% | 0.2% – 1.10% |
| Seagate Barracuda 7200.11 (ST31500341AS) |
1.5TB | 259 | 5.0 | 31.68% | 20.1% – 47.5% |
| Seagate Barracuda LP (ST31500541AS) |
1.5TB | 1,485 | 5.1 | 12.16% | 8.9% – 16.3% |
| Seagate Barracuda LP (ST31500542AS) |
2TB | 81 | 2.8 | 0.0% | 0.0% – 33.9% |
| Seagate Barracuda 7200.14 (ST3000DM001) |
3TB | 485 | 2.4 | 26.65% | 19.6% – 35.4% |
| Seagate Barracuda XT (ST33000651AS) |
3TB | 234 | 3.2 | 3.05% | 0.4% – 11.0% |
| Seagate Barracuda XT (ST4000DX000) |
4TB | 175 | 1.9 | 4.62% | 0.6% – 16.7% |
| Seagate Desktop HDD.15 (ST4000DM000) |
4TB | 14,803 | 1.0 | 3.06% | 2.5% – 3.7% |
| Seagate 6 TB SATA 3.5 (ST6000DX000) |
6TB | 495 | 0.1 | 2.41% | 0.1% – 13.5% |
| Toshiba DT01ACA Series (TOSHIBA DT01ACA300) |
3TB | 50 | 2.0 | 5.1% | 1.6% – 11.8% |
| Toshiba MD04ABA-V Series (TOSHIBA MD04ABA400V) |
4TB | 45 | 0.1 | 0.0% | 0.0% – 106.9 |
| Toshiba MD04ABA-V Series (TOSHIBA MD04ABA500V) |
5TB | 45 | 0.1 | 0.0% | 0.0% – 106.9% |
| Western Digital Red 3 TB (WDC WD30EFRX) |
3TB | 1045 | 0.9 | 12.87% | 8.5% – 18.7% |
| Western Digital 4 TB (WDC WD40EFRX) |
4TB | 45 | 1.0 | 9.01% | 0.2% – 50.2% |
| Western Digital Red 6 TB (WDC WD60EFRX) |
6TB | 450 | 0.3 | 7.77% | 3.4% – 15.3% |
| Note: Some of the HGST drives listed were manufactured under their previous brand, Hitachi. We’ve been asked to use the HGST name and we have honored that request. | |||||
Hard Drives In and Hard Drives Out
In our most recent hard drive study for Q4 2014, we analyzed 39,696 drives. There are 3,053 more drives in our Q1 2015 results. We actually deployed over 4,000 drives, as we replaced 324 failed drives as well as 631 Seagate 3TB suspect drives. During Q1 we deployed two Backblaze Vaults containing 900 drives each and 44 standalone Storage Pods with 45 drives each.
Observations and Trends
Looking at the Q1 hard drive reliability stats above, you can compare failure rates for the various drive models. The important thing to remember is that the table is a snapshot in time: Q1 of 2015. Below are the cumulative failure rates for the same 21 drive models beginning with Q4 of 2013 and progressing quarterly up through Q1 2015.
| Backblaze Hard Drive Failure Rates, Cumulative by Quarter | |||||||
|---|---|---|---|---|---|---|---|
| Name/Model | Size | 12/31/13 | 03/31/14 | 06/30/14 | 09/30/14 | 12/31/14 | 03/31/15 |
| HGST Deskstar 7K2000 (HDS722020ALA330) |
2TB | 1.10% | 1.08% | 1.09% | 1.03% | 1.06% | 1.15% |
| HGST Deskstar 5K3000 (HDS5C3030ALA630) |
3TB | 0.90% | 0.85% | 0.70% | 0.73% | 0.74% | 0.74% |
| HGST Deskstar 7K3000 (HDS723030ALA640) |
3TB | 0.90% | 1.54% | 1.46% | 1.55% | 1.81% | 1.83% |
| HGST Deskstar 5K4000 (HDS5C4040ALE630) |
4TB | 1.50% | 1.33% | 1.25% | 1.06% | 1.17% | 1.16% |
| HGST Megascale 4000 (HGST HMS5C4040ALE640) |
4TB | 2.67% | 1.90% | 1.86% | 1.43% | 1.18% | |
| HGST Megascale 4000.B (HGST HMS5C4040BLE640) |
4TB | 20.29% | 1.23% | 0.59% | 0.52% | 0.48% | |
| Seagate Barracuda 7200.11 (ST31500341AS) |
1.5TB | 25.40% | 22.27% | 22.98% | 23.02% | 23.41% | 24.12% |
| Seagate Barracuda LP (ST31500541AS) |
1.5TB | 9.90% | 9.87% | 9.67% | 9.56% | 9.93% | 10.18% |
| Seagate Barracuda LP (ST32000542AS) |
2TB | 7.20% | 8.03% | 8.18% | 9.96% | 9.63% | 9.93% |
| Seagate Barracuda 7200.14 (ST3000DM001) |
3TB | 9.80% | 13.92% | 17.65% | 27.15% | 28.31% | 28.26% |
| Seagate Barracuda XT (ST33000651AS) |
3TB | 7.30% | 6.53% | 6.33% | 6.08% | 5.59% | 5.27% |
| Seagate Barracuda XT (ST4000DX000) |
4TB | 0.75% | 0.56% | 0.45% | 1.12% | 1.61% | |
| Seagate Desktop HDD.15 (ST4000DM000) |
4TB | 3.83% | 3.03% | 2.73% | 2.75% | 2.83% | |
| Seagate 6TB SATA 3.5 (ST6000DX000) |
6TB | 1.70% | |||||
| Toshiba DT01ACA Series (TOSHIBA DT01ACA300) |
3TB | 4.63% | 3.48% | 4.20% | 4.81% | 4.23% | |
| Toshiba MD04ABA-V Series (TOSHIBA MD04ABA400V) |
4TB | 0.00% | |||||
| Toshiba MD04ABA-V Series (TOSHIBA MD04ABA500V) |
5TB | 0.00% | |||||
| Western Digital Red 3TB (WDC WD30EFRX) |
3TB | 3.20% | 8.78% | 9.07% | 6.96% | 6.49% | 7.90% |
| Western Digital 4TB (WDC WD40EFRX) |
4TB | 9.01% | |||||
| Western Digital Red 6TB (WDC WD60EFRX) |
6TB | 13.75% | 3.07% | 6.64% | |||
The cumulative view can be used to see trends over time as well as spot anomalous periods requiring further review. Remember that in the first quarter a given drive is deployed, the results can be skewed due to the limited number of drives and deployment hours.
Combining Views
Internally, we combine the cumulative and the current failure rates for each drive into a graph so we can quickly see if there are any changes requiring our attention. Below is a sample showing this information for the two 6TB drive models we currently deploy. The “overall rate” is the cumulative failure rate since the drive model was put into service and the “recent rate” is the failure rate over the past two months.
The data for Q1 2015 is available from our Hard Drive Data webpage where it can be downloaded for further study. The format for the 2015 data file changed with the addition SMART 22 attribute (raw and normalized) and four additional SMART stat pairs. Adjust your schemas accordingly and let us know if you find anything interesting.
