* Osier Yang <jyang@redhat.com> [2010-12-03 00:23]:
??? 2010???12???03??? 14:00, Ryan Harper ??????:
We recently had an issue with not being able to allocate the full capacity of a directory based storage pool. The reported value via pool-info was larger than what was available to the image creator.
Looking at the storage code, in virStorageBackendFileSystemRefresh() we're using statvfs, and reporting back
pool->def->available = ((unsigned long long)sb.f_bfree * (unsigned long long)sb.f_bsize);
Which is the amount of blocks available, including any root reservation if present on the filesystem.
This does't line up with df output , which at least on RHEL5 and 6 systems reports the available space from f_bavail, which excludes and reserved space.
Is it reasonable to have the available value line up with output from df and not report reserved space?
It's misleading not to exclude the reserved space, probly it will be nicer to report both the actually avaiable spaces and the reserved ones.
I argue the opposite. df doesn't show you the reserved space. the first thing someone does to compare the values between libvirt directory pool and df. I don't mind reporting both but, I've yet to see a tool to report the reserved value rather than the non-reserved.
- Osier
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-- Ryan Harper Software Engineer; Linux Technology Center IBM Corp., Austin, Tx ryanh@us.ibm.com