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Support for shingled magnetic recording devices

Support for shingled magnetic recording devices

Posted Mar 27, 2014 18:09 UTC (Thu) by wahern (subscriber, #37304)
In reply to: Support for shingled magnetic recording devices by fuhchee
Parent article: Support for shingled magnetic recording devices

Seagate has a nice description with illuminating diagrams:

http://www.seagate.com/tech-insights/breaking-areal-densi...

Basically, write heads are larger than read heads, but neither is going to get any smaller anytime soon. To get more data onto the platter, you can squeeze tracks together. The read head can still read each track individually, but the write head has to update multiple tracks at once, and this process can cascade.

That tracks are overlapped from the perspective of the write head is why it's called "shingled", like on a roof, and not because of a herpes zoster infection--which is the first thought I had :)


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Support for shingled magnetic recording devices

Posted Apr 4, 2014 10:50 UTC (Fri) by Jonno (subscriber, #49613) [Link]

> http://www.seagate.com/tech-insights/breaking-areal-densi...
While the Seagate description of SMR drives in the linked article is good, their comparison to conventional drives are disingenuous at best. No one has manufactured what they calls "Conventional" drives for some time now, writes to adjacent tracks already overlap, though not to the extent that SMR writes do (see diagram below for an illustration).

http://jon.severinsson.net/lwn/smr_track_layout.png

Support for shingled magnetic recording devices

Posted Jul 14, 2014 16:43 UTC (Mon) by ds... (guest, #97865) [Link]

It seems to me that it would be better to have a wider read head: if the drive needs to write n physical tracks at once, why not read n at once too?

Support for shingled magnetic recording devices

Posted Jul 14, 2014 18:03 UTC (Mon) by dlang (subscriber, #313) [Link]

it doesn't write n tracks in one pass, what it does is that it overlaps the tracks the way a row of shingles overlaps the row before them. This means that you can't just write wherever you want to, if you want to write a track you have to write the track that partially overlaps that track, the track that partially overlaps, the second track, etc.

it still takes n rotations of the media to write n tracks


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