1. A method of managing data within a data storage apparatus having a cache of volatile memory and non-volatile storage, the method comprising: receiving, from a set of external host devices, a set of host write commands to write data to the non-volatile storage; in a write-back caching manner, acknowledging completion of the set of host write commands after the data reaches the cache of volatile memory and prior to the data reaching the non-volatile storage, the data including host data and critical metadata; and after acknowledging completion of the set of host write commands, saving the data from the cache of volatile memory to the non-volatile storage, the critical metadata being saved from the cache of volatile memory to the non-volatile storage at a quicker rate than that of the host data; wherein the data storage apparatus is a data storage array having multiple storage devices; wherein receiving the set of host write commands includes obtaining a particular host write command from a host computer over a communications medium connecting the host computer to the data storage array; and wherein saving the data includes, in response to the particular host write command from the host computer, writing, as the critical metadata, operating system information to the multiple storage devices ahead of writing the host data to the multiple storage devices.