Summary: 3TB hard drives aren't quite as reliable as some of us thought, according to new Backblaze numbers based on a 100 petabyte cloud service using 34,881 consumer-grade disks.
By Jack Schofield for Jack's Blog |
By Jack Schofield for Jack's Blog |
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| Backblaze loads each Storage Pod with 45 hard drives so its reliability figures are not based on isolated samples. Photo credit: Backblaze
Backblaze, a cloud storage supplier, has just updated its January report on hard disk drive reliability, and the bad news is that 3TB drives are failing faster than expected.
Compared with January (reported here), the failure rate of Seagate 3TB drives has climbed from 9 percent to 15 percent, while the failure rate of Western Digital 3TB drives has jumped from 4 percent to 7 percent. As the chart below shows, only the more expensive Hitachi Deskstars — a brand that started life at IBM — have shown an improvement.
The September findings are based on Backblaze's use of 34,881 drives storing more than 100 petabytes of data.
All the drives are "consumer grade" rather than "enterprise" drives, because enterprise drives are more than twice the price. Backblaze says: "Even if there were no warranty, a 15 percent annual failure rate on the consumer 'desktop' drive and a 0 percent failure rate on the 'enterprise' drive, the breakeven would be 10 years, which is longer than we expect to even run the drives for."
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Backblaze's numbers are useful because it's buying drives in larger volumes than most companies, and tracking their performance more closely. And while other cloud storage companies are no doubt doing the same thing, they're not sharing their results.
The three least reliable drives tested are all Seagate Barracuda models. The Seagate Barracuda 7200.11 has had an annual failure rate of 24.9 percent, the 3TB 7200.14 of 15.7 percent, and the 1.5TB Barracuda LP of 9.6 percent. However, the 1.5TB drives are relatively old — their average age is 4.3 years — and the failure rate of hard drives increases with age.
The 3TB Western Digital Red hard drive is doing badly with a failure rate of 8.8 percent on what are basically new drives: the average age is only 6 months. By contrast, the failure rate on Backblaze's 3TB Hitachi Deskstar 5K3000 drives, which have an average age of 2.1 years, is only 0.7 percent.
Based on previous Backblaze research, the annual failure rate for all hard drives is 5.1 percent for the first 18 months, 1.4 percent for the next 18 months, and 11.8 percent for the year after that. Although this doesn't sound impressive, it still means that 80 percent of drives are still going strong after four years.
There are some hard drives that Backblaze has tried and won't use because they "just don’t work in the Backblaze environment". These include the energy-efficient "Western Digital Green 3TB drives and Seagate LP (low power) 2TB drives. Both of these drives start accumulating errors as soon as they are put into production," says Backblaze. "We think this is related to vibration."
Backblaze is still buying a lot of Seagate drives, and it has 9,619 Seagate Desktop HDD.15 drives with an average age of 6 months. Failed drives are replaced under warranty though there is, of course, a cost to removing and replacing drives. Companies not set up to do this economically should bear this in mind.
It's interesting that the Hitachi drives continue to perform well. As mentioned, the Deskstar drives were originally IBM Deskstars, until IBM sold that business to Hitachi. Last year, Hitachi sold it to Western Digital, and then Western Digital sold the Hitachi 3.5in drive business to Toshiba. The 2.5in drive business has become "HGST (a Western Digital company)" and an employee says "the two product lines (WD and HGST) are totally separate in both parts and manufacturing".
As hard drive buyers, we don't have any way of knowing if Hitachi drives will keep being as reliable as they have been … unless Backblaze tells us.
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