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Best Shrinkable ReiserFS Replacement?
paulkoan writes "I have been using ReiserFS for my file system across a few servers for some time now (follow the link below for details of my experience). I can't foresee the future of ReiserFS, but if I'm going to have to migrate as support diminishes, I'd like to begin that process now. My criteria are: in-kernel support, shrinkable, and has good recovery when the file system is not closed properly. That shrinkable requirement precludes a lot of options. What's a good replacement for ReiserFS?"
I initially chose ReiserFS because I was building a MythTV system and it was the recommended FS across the board, from small to large files. I've had good experiences with ReiserFS and it has had a pummeling. That MythTV box for example has a very volatile environment and loses power on a regular basis. I haven't lost any data through any of these outages.
Compare this to my brief foray into XFS on the same box, where 25% of the filesystem ended up in lost+found with numbers for filenames. When this happened a second time on a different system I decided XFS wasn't for me — and I really don't get the point of a journalled filesystem that will keep data relatively safe, but then remove any means to identify it when things go wrong.
But everyone has good and bad experiences with filesystems, ReiserFS included. XFS has a good rep, my experience aside.
I initially chose ReiserFS because I was building a MythTV system and it was the recommended FS across the board, from small to large files. I've had good experiences with ReiserFS and it has had a pummeling. That MythTV box for example has a very volatile environment and loses power on a regular basis. I haven't lost any data through any of these outages.
Compare this to my brief foray into XFS on the same box, where 25% of the filesystem ended up in lost+found with numbers for filenames. When this happened a second time on a different system I decided XFS wasn't for me — and I really don't get the point of a journalled filesystem that will keep data relatively safe, but then remove any means to identify it when things go wrong.
But everyone has good and bad experiences with filesystems, ReiserFS included. XFS has a good rep, my experience aside.
With this kind of configuration, no matter what you do in term of journaling, you will *always* loose data when power fails during I/O operations.
Not sure if this is just confused terms or 'assumed' because of the chain involved you describe.
Dealing with non OS/FS level caches in devices is not something that 'always' equals data loss, as 99% of the devices have methods to signal the OS when a write is complete from cache and when it is only cached waiting write.
I can even give you a simple example of this. NTFS and Vista know what is written and not just device cached, and adds full journaling on top of this.
If this information wasn't available to the OS, then journaling is a wasted technology.
So, devices do let the OS/FS know where the data 'really' is, it is up to the OS to be smart enough to handle this.
Go check out storage device interface specifications, and you will find the mechanisms of how the OS and drivers get this information.
In the Microsoft NT world, turning off write caching in a device is just killing your performance 99% of the time, it is not making your data safer.
Sadly, in the Linux/*nix world, it is a recommended option because the device cache is not something most *nixes or *nix FSs pay attention to very well, until you get to enterprise solutions with very specific devices/drives married to the server installation.