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author | Richard W.M. Jones <rjones@redhat.com> | 2007-09-27 18:59:54 +0100 |
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committer | Richard W.M. Jones <rjones@redhat.com> | 2007-09-27 18:59:54 +0100 |
commit | 5616e76a5a01656aa0dcc323fcd1fcd77764e638 (patch) | |
tree | 7e37726337d16b5b4a1d3216eaa97d18668d4bc6 /virt-df/README | |
parent | 3d742c162cbcb38663da580f1dff58db992f1a22 (diff) | |
download | virt-top-5616e76a5a01656aa0dcc323fcd1fcd77764e638.tar.gz virt-top-5616e76a5a01656aa0dcc323fcd1fcd77764e638.tar.xz virt-top-5616e76a5a01656aa0dcc323fcd1fcd77764e638.zip |
* configure.ac: Changed version to 0.3.2.9.
* Makefile.in: Re-enable virt-df.
* virt-df/virt_df*.ml: Mostly finished off the core of virt-df.
Ext2/3 support. No LVM as yet.
* virt-df/README: Added README file.
Diffstat (limited to 'virt-df/README')
-rw-r--r-- | virt-df/README | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/virt-df/README b/virt-df/README new file mode 100644 index 0000000..7b53f3e --- /dev/null +++ b/virt-df/README @@ -0,0 +1,35 @@ +$Id$ + +virt-df is a 'df' tool for printing out the used and available disk +space in all active and inactive domains. Without this tool you would +need to log in to each domain individually or set up monitoring. + +It is only a proof-of-concept. Please bare in mind the following +limitations when using this tool: + +(1) It does not work over remote connections. Part of the reason why +I wrote virt-df was to get an idea of how the remote storage API for +libvirt might look. + +(2) It only understands a limited set of partition types. Assuming +that the files and partitions that we get back from libvirt / Xen +correspond to block devices in the guests, we can go some way towards +manually parsing those partitions to find out what they contain. We +can read the MBR, LVM, superblocks and so on. However that's a lot of +parsing work, and currently there is no library which understands a +wide range of partition schemes and filesystem types (not even +libparted which doesn't support LVM yet). The Linux kernel does +support that, but there's not really any good way to access that work. + +The current implementation uses a hand-coded parser which understands +some simple formats (MBR, LVM2, ext2/3). In future we should use +something like libparted. + +(3) The statistics you get are delayed. The real state of, for +example, an ext2 filesystem is only stored in the memory of the +guest's kernel. The ext2 superblock contains some meta-information +about blocks used and free, but this superblock is not up to date. In +fact the guest kernel may not update it even on a 'sync', not until +the filesystem is unmounted. Some operations do appear to write the +superblock, for example fsync(2) [that is my reading of the ext2/3 +source code at least]. |