5.1. Docker Volume Creation Options

When creating a Docker volume in CLI, GUI, or docker compose file, you need to specify ploop as the volume driver. This is the only requirement. In addition, you can specify various optional volume parameters. The following parameters are currently supported:

Parameter Description
size

Volume size.

Example: size=10G for a volume on which one can store up to 10GB of data.

tier

Virtuozzo Storage tier to use for the volume. Tier 0 is the fastest, and tier 3 is the slowest. Do not use this option if you have not configured tiers in your Virtuozzo Storage installation.

Example: tier=2.

mode

For advanced users only. The default value should work fine in most cases.

Ploop image mode (format) to use for the volume. Possible values are expanded, preallocated, and raw.

  • expanded (default), the image will grow according to the needs of the underlying file system (thin provisioning).
  • preallocated, same as expanded, except all the file blocks are allocated during creation.
  • raw, 1:1 mapping between the image file and the device it represents.

Example: mode=preallocated.

clog

For advanced users only. The default value should work fine in most cases.

Log2 of ploop cluster block size, in 512-byte sectors. Default is 1M cluster block size, which corresponds to clog=11 (i.e. 2^11 = 2048 sectors, 2048*512 = 1M). Sensible values are in the range from 7 to 13.

Example: clog=12.