Originally posted by pal666
View Post
I mentioned this as a stop gap.
XLV is simple to forget had existed. So XFS should in time work well behaved with the system device mapper system.
This new tricks of XFS gets very interesting on the device management side.
If XFS file system can be modified to straight up mount using a file instead of device while able still able to use device this makes you ask another question. Can device mapper subsystem be modified to work with files instead of devices as well.
This opens up a very different path. If device mapper doing raid is working on files in a generic way you end up with like ZFS and BTRFS device management but it generic so you could have a file level raid with multi different file system under it.
Yes the idea of integrating device management with file system maybe right. But making device management part of file system might be wrong. The XFS path is can we make file system and device management work cooperatively with each other so we don't have multi copies of device management.
Really software raid under file system and software raid above/part of file system have to do most of the same things.
Originally posted by pal666
View Post
You don't need COW structures in the metadata if you do it from the data/block layer as XFS is lining up to-do and how Ext3cow did it.
Non Cow metadata in snapshots has been is quite usable its simple to forget working cooperatively with the device management XFS has had the block layer providing COW so having functionality of a full copy on write file system without being a copy on write file system. There have been issues with ENOSPC what has made using block level COW not recommend again the new tricks for XFS is addressing this issue.
The issue here is XFS treats itself as only part of the solution and attempt to avoid implementing everything itself where it can.
Its going to be interesting to see how the XFS changes play out remember the changes will not just be limited to XFS we should expect to see changes in the device mapper as well. Yes XFS developers work on issues in the device mapper in the Linux kernel.
Comment