How to reduce cache size and how to know the real downloading image data?

[wangguangju]

I started a container using an image in nydus format, but I how some questions:

1, The cache data occupies a large space and does not save disk space on the machine. How do I reduce the size of the cache? Is it configurable?

2, How do I know how much image real data has been downloaded in lazy load mode? The current snapshot directory shows the data size and does not represent the actual data downloads?

root@bogon:/var/lib/containerd/io.containerd.snapshotter.v1.nydus$ du -sh *
1.3G cache
0 config
284K logs
172K metadata.db
80K nydus.db
1.2G snapshots
0 socket

[imeoer]

1. configure nydusd config.json to set fs_prefetch.enable: false, it means that only on-demand data will be downloaded.
2. du -sh /var/lib/containerd/io.containerd.snapshotter.v1.nydus/cache