Can I and *should* I mirror an existing LVM root partition on an SSD with another SSD?

bertieb

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Jul 1, 2020
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bertieb.org
Background: I have a 'server' running Proxmox that I used for self-hosting a number of low-intensity services mainly for myself. This 'server' is my old repurposed HEDT desktop machine. It is also used for storage, and has raidz2 running across 6 spinning rust disks. The system (root, etc) runs on LVM and not the ZFS raidz2 drives, stored on an old Samsing 840 128GB (~111GB formatted) SSD. I am removing another old Crucial 256GB (CT256MX1) SSD
and wondered about putting it to use in this machine since it has SATA ports to spare.

I'm happy to post output of lsblk, fdisk -l etc if any would be helpful.

My thinking: conceptually, I could split the 256GB SSD in two- have a (RAID1) mirror LV of the existing /root, and use the rest of the space for other purposes? (like Docker, instead of using a slower overlay2 zvol arrangement) Can this be done relatively easily?

My interest in doing so is threefold: 1) keep older storage hardware in use 2) provide some degree of redundancy for the server's root lv 3) get a minor bump in read throughput for the root LV. If none of these hold true there's little point in me doing so- I might be better migrating from the smaller SSD to the bigger one; or just adding the bigger one as extra SSD storage (or a read cache for the raidz2?).

In case it's not totally obvious- this is an amateur / non-pro / non-enterprise setup, and I'm on a budget so repurposing and reusing hardware is a great boon!
 
Alternatively, I could benchmark the drives, keep whichever is better for my root partition and use the other as an L2ARC. This might be more sensible.
 

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