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On Sun, Sep 3, 2017 at 6:41 PM, Grant <emailgrant@×××××.com> wrote: |
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>>>>> My new laptop uses /dev/nvme0n1 instead of /dev/sda which conflicts |
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>>>>> with the script I use to manage about 12 similar laptops running |
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>>>>> Gentoo. Is there a udev method for renaming the disk that will work |
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>>>>> well with any USB disks that happen to also be attached? |
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>>>> |
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>>>> I'm not certain what you mean by that, but I would guess that you want |
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>>>> the nvme disk to show up as /dev/sda, and the USB disk(s) to show up |
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>>>> as /dev/sd[b-z]. |
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>>>> |
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>>>> It is not possible to accomplish this using udev; the kernel owns the |
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>>>> /dev/sdX device namespace, and will sequentially create devices nodes |
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>>>> for SCSI-like block devices using that namespace. There is no way to |
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>>>> change that using a udev rule. |
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>>> |
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>>> |
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>>> Can I rename /dev/sda to /dev/sd[b-z] if it's attached via USB, and |
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>>> then rename /dev/nvme0n1 to /dev/sda if /dev/nvme0n1 exists? |
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>>> |
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>>> Alternatively, can I rename /dev/sda to /dev/sd[b-z] if /dev/sda and |
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>>> /dev/nvme0n1 exist, and then rename /dev/nvme0n1 to /dev/sda if |
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>>> /dev/nvme0n1 exists? |
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>> |
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>> You might technically be able to do it, but I would guess it would |
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>> cause some nasty race conditions between the kernel and udev. It's a |
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>> bad idea. |
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> |
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> |
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> Is it the conditionals that cause this to be a bad idea? Because I |
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> believe udev has functionality designed to rename devices exactly like |
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> this. |
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|
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udev doesn't provide any functionality to rename device nodes. You can |
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adjust their permissions, and create symlinks, but there is no direct |
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way to rename them. |
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|
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To rename a device node in a udev rule, you would have to call an |
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external command, which udev knows nothing about. After having renamed |
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it this way, the information in the udev device database would no |
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longer be consistent, and any future device events would not work |
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properly. |
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|
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I would suggest you utilize the existing symlinks in one of the |
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/dev/disk/ sub-directories, or create some udev rules to create your |
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own symlinks based on whatever metadata you wish. I would also suggest |
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you read the udev(7) manual page. |
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|
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Trying to coerce your nvme device to look like an sd device is really |
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the wrong approach to solving your problem. |
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