I have a folder containing a lot of KVM qcow2 files, they are all sparse files. Now I need to get the total size of folder, the qcow2 file size should be counted as apparent size(not real size).
for example:
image: c9f38caf104b4d338cc1bbdd640dca89.qcow2 file format: qcow2 virtual size: 100G (107374182400 bytes) disk size: 3.3M cluster_size: 65536
the image should be treated as 100G but not 3.3M
originally I use statvfs() but it can only return real size of the folder. then I switch to ‘du –apparent-size’, but it’s too slow given I have 10000+ files and it takes almost 5 minutes to caculate.
anybody knows a fast way that can get the size of folder counting qcow2’s virtual size? thank you
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Answer
There is no way to find out this information without stat()ing every file in the directory. It is slow if you have this many files in a single directory. stat() needs to retrieve the inode of every single file.
Adding more memory might help due to caching.