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Rich Freeman wrote: |
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> On Fri, May 22, 2020 at 11:32 AM Michael <confabulate@××××××××.com> wrote: |
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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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> |
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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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> |
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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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> |
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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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The thing about the one I have now in use by LVM for /home, one is SMR |
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and one is PMR. Even if the OS is aware, does it even know which drive |
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the data is going to end up being stored on? I'm pretty sure since the |
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PMR drive was in use before the SMR that the PMR is likely full. From |
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my understanding, LVM doesn't balance the data out. It will fill up a |
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drive and then move on to the next. If you add another, it will fill up |
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the 2nd drive and then start on the newly added drive. Maybe it does do |
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some magic but does the OS know which drive data is going to hit? |
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It seems to me that we could end up stuck with SMR or pay a premium for |
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PMR. That's the part that worries me. I'm not saying SMR isn't good |
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for a lot of folks but for us power type users, it matters. You get |
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into servers and it matters a whole lot I'd imagine. |
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Maybe I need to buy some drives before I can't even get them at a |
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affordable price at all??? |
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Dale |
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:-) :-) |
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P. S. Thanks to Michael for the info. I'll read it in a bit. Having a |
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little sewer problem. Dirty job. -_o |
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