Re: btrfs with raid5/6

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




It's up to you. I'd prefer LUKS/dmcrypt.
So do I. But I have a related concern:

I currently do ext4 <-> dm-crypt <-> linux-software-raid <-> hdds

However Linux Software Raid (mdadm) does not protect you from silent data loss, because it does not store checksums in it's metadata. So what mdadm does is, it compensates for failed devices, or blocks, if the device reports them as bad. But I can NOT correct data, that was e.g. corrupted by the SATA controller or backplane. See http://neil.brown.name/blog/20100211050355 "Smart or simple RAID recovery??" for more information.

Btrfs (like ZFS) can be the solution here, as it stores CRC checksums with all data and metadata. RAID5 with protection from silent data loss is promised to be implemented in the future.
A setup on top of dm-crypt would look as follows:

btrfs <-> multiple dm-crypt partitions <-> multiple devices

However in the past I experienced very disappointing results, if raid is running on top of dm-crypt partitions. If I remove hdds from such a setup the dm-crypt partition wont disappear. It won't propagate the error to the software raid on top of it (not familiar with the implementation details, maybe mdadm is to blame here). And finally it won't even let itself be deleted without restart (I think the last issue has been fixed in the meantime).

I urge the dm-crypt developers to improve this situation with raid on top of dm-crypt, be it with mdadm or btrfs. Solutions for other long-time annoying issues like insufficient threading support, and the lack of discard support, would be appreciated too. :P I know the OSS pradigm is provide patches yourself. Would you be accepting patches?

Sincerly,
Markus

_______________________________________________
dm-crypt mailing list
dm-crypt@xxxxxxxx
http://www.saout.de/mailman/listinfo/dm-crypt


[Index of Archives]     [Device Mapper Devel]     [Fedora Desktop]     [ATA RAID]     [Fedora Marketing]     [Fedora Packaging]     [Fedora SELinux]     [Yosemite News]     [KDE Users]     [Fedora Tools]     [Fedora Docs]

  Powered by Linux