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On Fri, May 22, 2020 at 11:32 AM Michael <confabulate@××××××××.com> wrote: |
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> |
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> An interesting article mentioning WD Red NAS drives which may actually be SMRs |
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> and how latency increases when cached writes need to be transferred into SMR |
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> blocks. |
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Yeah, there is a lot of background on this stuff. |
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You should view a drive-managed SMR drive as basically a journaled |
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filesystem/database masquerading as a virtual drive. One where the |
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keys/filenames are LBAs, and all the files are 512 bytes long. :) |
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Really even most spinning drives are this way due to the 4k physical |
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sectors, but this is something much easier to deal with and handled by |
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the OS with aligned writes as much as possible. SSDs have similar |
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issues but again the impact isn't nearly as bad and is more easily |
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managed by the OS with TRIM/etc. |
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A host-managed SMR drive operates much more like a physical drive, but |
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in this case the OS/application needs to be SMR-aware for performance |
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not to be absolutely terrible. |
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-- |
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Rich |
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