====== Linux Guests ======

Linux Guest on BTRFS:
  * BTRFS with single copy of meta, system and data
  * I/O is better on modern guest Kernel 6.1 (vs 5.10)
  * I/O is better whem VM storage is "no cache"
    * sync writes goes to ZFS ZIL
    * With "Writeback" cache - ZFS ZIL was not utilized so high like with "no cache"


Block sizes:

  * Default ''zvol'' ''volblocksize'' was 8k
  * Latest Proxmox creates ''zvols'' with 16k ''volblocksize''

So it is best to fit guest block sizes into ZFS block (16k) sizes:
  * mkfs.btfs options: --nodesize 16k
  * btrfs mount options: -o noatime
  * mkfs.ext4 options: -b 4096 -E stride=4,stripe-width=8
  * ext4 mount options: -o noatime,user_xattr