# device-mapper problem

## StaraDama

```
cdrom: open failed.

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table

device-mapper: dm-linear: Device lookup failed

device-mapper: error adding target to table
```

How to fix that?

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## PietdeBoer

hey,

iam having the same error.. i read it has something to do with the device mapper .. trying to find a non existing device..

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## Falchion

same problem here, also no solution...

I had it after I emerge hotplug.

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## tradenet

I also having the same problem.   :Shocked:   I have no problem mounting the device /dev/cdrom after boot up.

Any movement on this issue?

Oh BTW, I did change fstab to reflect the changes. ie /dev/cdrom  /mnt/cdrom iso9660 noauto, ro 0 0

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## tradenet

Sorry,

But can anyone please explain or direct me to what's going on here.

Thanks.

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## TBW

I have the same problem.   :Crying or Very sad: 

It is the first time, i installed Gentoo. 

I configured the Kernel and at booting there was error with the dm_mod -> ist was not installed 

so i reconfigure the Kernal and install dm_mod and now i get the error like StaraDama.

```
device-mapper: dm-linear: Device lookup failed 

device-mapper: error adding target to table
```

I using reiserfs for the root partition. I read something on a website that you need dm_mod for encryption.

But i dont use encryption.

I installed the 2.6.15 gentoo-r1 Kernel 

Anybody knows a solution?

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## tradenet

Would love to know that solution.  :Shocked: 

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## tradenet

Is this some how related:

https://forums.gentoo.org/viewtopic-t-417237-highlight-dmlinear+cdrom.html

 :Question:   :Question: 

Anyone?

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## thesnowman

I recompiled my kernel with Mirror target support and got rid of these errors.  Previous kernel was working fine prior to lvm2/device-mapper upgrade.  Not sure which one caused the problem as they were both upgraded a few days ago and I've only just rebooted to find this problem.

```
Device Drivers  --->  Multi-device support (RAID and LVM)  --->  <*>     Mirror target (EXPERIMENTAL)
```

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## tradenet

 :Sad:   Well, I've tried that too. Still getting that device mapper error. I get a couple of "cdrom: open failed." messages in between the "device-mapper: error adding target to table" errors. What else have you enable in:

```

Device Drivers  --->  Multi-device support (RAID and LVM)  ---> 

```

??

I've disabled RAID support completely.

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## thesnowman

The reason I tried adding Mirror target support is because of this webpage.

I don't have RAID support either:

```
Device Drivers  --->  Multi-device support (RAID and LVM)  --->

[*] Multiple devices driver support (RAID and LVM)

< >   RAID support

<*>   Device mapper support

< >     Crypt target support

< >     Snapshot target (EXPERIMENTAL)

<*>     Mirror target (EXPERIMENTAL)

< >     Zero target (EXPERIMENTAL)

< >     Multipath target (EXPERIMENTAL)
```

----------

## tradenet

OK, what I did was I unemerged lvm2 evms AND device-mapper. ie emerge -C lvm2 evms device-mapper. Did a revdep-rebuild to make sure nothing is broken. Voila! No more device mapper errors.

----------

