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On Fri, Dec 21, 2012 at 5:42 AM, Helmut Jarausch |
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<jarausch@××××××××××××××××.de> wrote: |
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> Hi, |
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> |
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> I'd like to put some subdirectory trees (of / and of /usr and of /home) onto |
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> an SSD. |
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> For that I'd like to count the disk accesses which go to a given |
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> subdirectory tree |
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> in some given time intervall. |
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> |
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> Is there any utility which can measure this? |
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> |
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> Many thanks for a hint, |
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> Helmut. |
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> |
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|
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Hi Helmut, |
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Only responding to say I'd been looking for something to do the |
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same thing myself and haven't found anything. |
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|
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That said, a couple of points: |
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|
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1) You should be able to watch for issues using smartctl, assuming a |
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modern SSDs. |
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|
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2) In a post where I asked about this sort of stuff in the Vertex |
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forums I received the following response from folks who seem to have |
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more experience than I. Of course, take this with a grain of salt: |
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|
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[QUOTE] |
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Just using round numbers and assuming effective wear leveling, your 30 |
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GB file may get rewritten once a month. That's 25% of the 128 GB |
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drive, so each NAND cell will get rewritten 3 times a year. If the |
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NAND is good for 10,000 rewrites, you have LOTS of years available... |
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|
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Even if it's rewritten every day, that's 100 NAND rewrites/year, or |
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100 years of NAND life based on rewrites. |
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|
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You can use any numbers you want, but it will still likely come out to |
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"longer than we care about"... |
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[/QUOTE] |
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|
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Keep in mind that the idea of 'effective wear leveling' is |
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___really___ important here. Unlike an HD, SSDs do not write over and |
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over to the same location forever. If a block of the drive starts to |
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get heavily used, in terms of number of writes, then firmware will |
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move the block to another location and remap the address. This happens |
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in the drive, not by the OS, so it's invisible to us. (First order |
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anyway - there are probably ways to find out but I'm not looking for |
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those.) |
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|
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Anyway, as there hadn't been any responses I thought I would... |
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|
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Cheers, |
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Mark |