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New Seagate Shingled Hard Drive Teardown
New submitter Peter Desnoyers writes: Shingled Magnetic Recording (SMR) drives are starting to hit the market, promising larger drives without heroic (and expensive) measures such as helium fill, but at a cost — data can no longer be over-written in place, requiring SSD-like algorithms to handle random writes.
At the USENIX File and Storage Technologies conference in February, researchers from Northeastern University (disclaimer — I'm one of them) dissected shingled drive performance both figuratively and literally, using both micro-benchmarks and a window cut in the drive to uncover the secrets of Seagate's first line of publicly-available SMR drives.
TL;DR: It's a pretty good desktop drive — with write cache enabled (the default for non-server setups) and an intermittent workload it performs quite well, handling bursts of random writes (up to a few tens of GB total) far faster than a conventional drive — but only if it has long powered-on idle periods for garbage collection. Reads and large writes run at about the same speed as on a conventional drive, and at $280 it costs less than a pair of decent 4TB drives. For heavily-loaded server applications, though, you might want to wait for the next generation. Here are a couple videos (in 16x slow motion) showing the drive in action — sequential read after deliberately fragmenting the drive, and a few thousand random writes.
At the USENIX File and Storage Technologies conference in February, researchers from Northeastern University (disclaimer — I'm one of them) dissected shingled drive performance both figuratively and literally, using both micro-benchmarks and a window cut in the drive to uncover the secrets of Seagate's first line of publicly-available SMR drives.
TL;DR: It's a pretty good desktop drive — with write cache enabled (the default for non-server setups) and an intermittent workload it performs quite well, handling bursts of random writes (up to a few tens of GB total) far faster than a conventional drive — but only if it has long powered-on idle periods for garbage collection. Reads and large writes run at about the same speed as on a conventional drive, and at $280 it costs less than a pair of decent 4TB drives. For heavily-loaded server applications, though, you might want to wait for the next generation. Here are a couple videos (in 16x slow motion) showing the drive in action — sequential read after deliberately fragmenting the drive, and a few thousand random writes.
More than a head per side? It's been attempted, and turned out it's not really worth it. It's a lot of extra complication for not that much benefit. Heads are expensive and generate heat, so it works out to close 2X the price anyway, plus an increased change of failure. Easier and safer to just add another drive.
These days there are SSDs too.
Find me an 8TB SSD that is even within spitting disttance (hell, within ICBM distance) of $300 and you win the prize, otherwise the suggestion is sless. Hint: Not today, not next year. Possibly this decade . The cost has come down a ton, but it was absolutely astronomical before.
The systems I'm buying now will be obsolete by the time SSD can even think about touching hard drives in terms of capacity per $. Typically, the ONLY reason to go full SSD now for large storage capacities is because you absolutely need the performance and are willing to pay essentially "whatever it costs" (at least 8x+ the price) because it's that important to get the IOPS. Maybe by the end of next year we'll get it down to "only" 4x the price (not counting that though because price per GB for large capacity hard drives still continutes to fall, balancing out a part of the cost reduction in SSDs).