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Re: udev causing data loss?

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Douglas A. Tutty wrote:

> Lets say you have an old server with 12 disks on two scsi busses an
> you're using mdadm (rather than a hardware raid card).  Lets say that
> all 12 drives are in one array (just to make life interesting).  One of
> those disks dies.  
> mdadm would have assembed the array (before the failure) and you can get
> a list of /dev/sd? devices that make up the array.  When a drive fails,
> you get a message, presumably telling you that e.g. /dev/sde has failed.
> How do you know which drive has failed so that you can swap it?

Hmmm. That's something I haven't hit yet.

udev's a wonderful idea, and it almost works. If the installer (software
or wetware) created vendor / model / serial# rules for the drives it
works with, that would help a lot. There are just too many places in
*nix that expect at least some of the device names to hold still.

Here's another issue:

There's a DLT drive in my LAN server. mt, the mag tape utility, defaults
to a device name "tape" for it's target. But udev creates a directory in
/dev with that name, so I have to specify a target for mt. This isn't a
major problem -- I'd already done that in my scripts anyway -- but it's
 another little flaw.

I created an early, local udev rule to create the SYMLINK, but the only
reason it works is that the kernel refuses when udev asks it to create
the directory (because /dev/tape already exists).

- --
Glenn English

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