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On 05/07/2013 10:49 AM, Stroller wrote: |
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> |
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> On 6 May 2013, at 21:07, Randolph Maaßen wrote: |
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> |
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>> - When a file is deleted the file system marks the block device |
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>> sectors as free and sends the TRIM command to the SSD and the SSD |
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>> really frees the underlying cell / breaks the cell - section allocation. |
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> |
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> So if I'm writing a new filesystem, I have to make sure it make the TRIM |
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> systemcall, otherwise it'll break with SSDs? |
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|
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Not exactly. What the TRIM system call really does is give the drive |
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hints about where the boundaries of your data really are, so that it |
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knows what parts of the disk's space it can take more liberties with. |
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|
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As a rough analogy, imagine you're helping a friend fill a bunch of |
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crates. Perhaps the friend told you he doesn't really care about some of |
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the stuff, and you realize you can get stuff done more effectively by |
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dumping a crate full of junk into the trash and putting other stuff |
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(stuff he cares about) into it. |
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|
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This helps improve disk lifetime and efficiency, but it's not strictly |
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necessary for functionality; nobody's truly harmed by having a crate of |
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junk hanging around, since the owner can always replace stuff in it at |
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their leisure, anyway. It's just more efficient if the crate's empty |
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when he goes to put stuff in it. |
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