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51 lines
1.6 KiB
51 lines
1.6 KiB
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dm-ebs |
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====== |
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This target is similar to the linear target except that it emulates |
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a smaller logical block size on a device with a larger logical block |
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size. Its main purpose is to provide emulation of 512 byte sectors on |
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devices that do not provide this emulation (i.e. 4K native disks). |
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Supported emulated logical block sizes 512, 1024, 2048 and 4096. |
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Underlying block size can be set to > 4K to test buffering larger units. |
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Table parameters |
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<dev path> <offset> <emulated sectors> [<underlying sectors>] |
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Mandatory parameters: |
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<dev path>: |
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Full pathname to the underlying block-device, |
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or a "major:minor" device-number. |
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<offset>: |
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Starting sector within the device; |
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has to be a multiple of <emulated sectors>. |
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<emulated sectors>: |
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Number of sectors defining the logical block size to be emulated; |
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1, 2, 4, 8 sectors of 512 bytes supported. |
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Optional parameter: |
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<underyling sectors>: |
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Number of sectors defining the logical block size of <dev path>. |
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2^N supported, e.g. 8 = emulate 8 sectors of 512 bytes = 4KiB. |
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If not provided, the logical block size of <dev path> will be used. |
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Examples: |
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Emulate 1 sector = 512 bytes logical block size on /dev/sda starting at |
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offset 1024 sectors with underlying devices block size automatically set: |
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ebs /dev/sda 1024 1 |
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Emulate 2 sector = 1KiB logical block size on /dev/sda starting at |
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offset 128 sectors, enforce 2KiB underlying device block size. |
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This presumes 2KiB logical blocksize on /dev/sda or less to work: |
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ebs /dev/sda 128 2 4
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