Messages in this thread | | | Date | Thu, 25 Jun 1998 11:45:43 +0200 | From | Florian Lohoff <> | Subject | Re: (reiserfs) Re: LVM / Filesystems / High availability |
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On Wed, Jun 24, 1998 at 01:51:49PM -0400, Theodore Y. Ts'o wrote: > Date: Wed, 24 Jun 1998 13:17:33 +0200 > From: Florian Lohoff <flo@quit.mediaways.net> > > There are logically no holes. If you have to take a PE out of service in > the middle you multiple choices: > > 1. Shrink the filesystem by the size of one PE and exchange > the PE in the middle by the PE got free at the end > (Assuming Grow-/Shrinking always happens at the end, otherwise > you *NEED* PE/LV aware FSes) > 2. Replace the PE by another PE in the Volume Group beeing > completely transparent to the Filesystem. > > OK, suppose I have a 54 terrabyte filesystem, with all PE's in use, and > I need to remove a 9 gigabyte disk from the middle of the filesystem, > because it's failing. > > I can't do (2) because I don't have a spare PE to use. > > I could do (1) but that would mean temporarily copying *more* data to > the failing 9 gigabyte disk as part of the compaction process, thus > putting that data at risk. The increase disk activity would also make > it more likely for the disk to fail completely. Once the filesystem has > been compacted you now have space to exchange the PE, but that involves > needless 9 gigabyte copy on top of the overhead of the filesystem > compaction.
This is why you should first attach a new 9GB Disk attach it to you volume group and copy all data from the failing to the new drive. Ok ... i see this as a problem
> There are plenty of filesystem implementation efforts which are trying > to do this. Reiserfs, dts, lfs, among others. In my experience there > are far more filesystem projects started than actually finish, although > I'll be the first to acknowledge that there are some pretty sharp people > working on some of the other filesystems. In the true Bazaar model, > we'll see which approach results in a stable, performant and robust > filesystem first. It should be an interesting experiment. > > - Ted
We will see ... i myself wont be happy to see this in the ext2 instead of splitting the complexity to different abstraction layers to bring down complexity and increase reliability and flexibility.
Flo -- Florian.Lohoff@mediaWays.net +49-5241-80-7085 aka flo@mini.gt.owl.de @HOME +49-5241-470566
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