# Ext4 (and ext3 I think) dm and barrier feature problem.

## SlashBeast

Hi.

I move my rootfs and home from reiserfs to ext4 and I have problem(?)

```
[   43.372892] EXT4-fs: barriers enabled

[   43.396100] kjournald2 starting.  Commit interval 5 seconds

[   43.396893] EXT4 FS on dm-1, internal journal on dm-1:8

[   43.396898] EXT4-fs: delayed allocation enabled

[   43.396903] EXT4-fs: file extents enabled

[   43.436896] EXT4-fs: mballoc enabled

[   43.436903] EXT4-fs: mounted filesystem with ordered data mode.

[  114.478482] JBD: barrier-based sync failed on dm-1:8 - disabling barriers

```

I use cryptsetup to encrypt whole rootfs (dm-0) and home (dm-1), Why barrier dont work on my hdd? DeviceMapper problem, cryptsetup or something else? 

The same JBD error for dm0 and dm1.

Its a bug or a feature?

/sorry about my english./

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## Paczesiowa

exactly the same problem here. anyway it only sounds scary because everything seems to work.

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## Cyker

Are you using any kind of RAID?

I know the built-in RAID doesn't support barriers, and with the addition of journal checksums they become less critical anyway so I just use the barriers=0 option in my fstab to get rid of that message.

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## Dairinin

AFAIK write barriers are not supported by device mapper

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## SlashBeast

No raid, only cryptsetup.

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## Dairinin

 *SlashBeast wrote:*   

> No raid, only cryptsetup.

 

md (raid) != dm (lvm, dm-crypt)

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## selig

True, I'm using XFS on an encrypted disk using device mapper and it disables barriers too.

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