Root on ZFS - is it normal to not have a (ZFS) cachefile defined for the rpool?

[ZPrime]

My system is just a single node, running with a pair of SSDs in a ZFS mirror. It was setup as 100% ZFS using the Proxmox installer.

I wanted to run zdb to check on some info about the pool (specifically I was curious about the ashift / block size setting).

zdb comes back with this error:
cannot open '/etc/zfs/zpool.cache': No such file or directory

Now, I'm kind of thinking this might be expected behavior - presumably with root on ZFS, we're booting from a temporary ramdisk, and i don't know how it'd be possible to read in a cachefile from that scenario?

Or is there some way to set the cachefile and make everything work nicely... and if so, why wasn't this done by the installer?

 

[fabian]

you don't need a cache file for zdb to work - which command did you want to run?

a cache file mainly makes sense on systems with lots of (possibly irrelevant) storage attached, as without it, the system will scan *all block devices* on bootup, importing any found zpools, which can take a while

 

[ZPrime]

I wanted to run zdb -C against the rpool. Eventually I found the -e flag which makes it work... I just found it odd that there was no cachefile configured by default.

 

[gjani]

Hey @ZPrime, would you mind sharing an example of the command(s) that works for you?
I have a couple pools and only one is recognized by zdb. Idk why. The pools were created with different versions of zfs but I don't see a clear reason.