ZFS

Since fall 2015 the default compression algorithm in ZOL is LZ4 and since choosing compression=on means activate compression using default algorithm then your pools are using LZ4 → http://open-zfs.org/wiki/Performance_tuning#Compression

# Check if LZ4 is active
zpool get feature@lz4_compress rpool

• ZPool is the logical unit of the underlying disks, what zfs use.
• ZVol is an emulated Block Device provided by ZFS
• ZIL is ZFS Intent Log, it is a small block device ZFS uses to write faster
• SLOG is Seprate Intent Log
• ARC is Adaptive Replacement Cache and located in Ram, its the Level 1 cache.
• L2ARC is Layer2 Adaptive Replacement Cache and should be on an fast device (like SSD).

• ZFS: Tips and Tricks
• Install on a high performance system

• SLOG can speedup synchronous only writes
  • The ZIL's purpose is to protect you from data loss. It is necessary because the actual ZFS write cache, which is not the ZIL, is handled by system RAM, and RAM is volatile.
  • In default setup of ZFS, synchronous writes are not handled by ZIL
  • The ZIL doesn't need to be very big. Find the transfer speed of the fastest disk in your array and multiple by 10s, this is about how big your ZIL should be.
  • http://nex7.blogspot.com/2013/04/zfs-intent-log.html
  • https://www.cyberciti.biz/faq/how-to-add-zil-write-and-l2arc-read-cache-ssd-devices-in-freenas/
• L2ARC is a read cache. L1 in memory, L2 on disk

blkid
/dev/nvme0n1p4: PARTLABEL="ZIL" PARTUUID="d6da74cd-32e7-4286-8e78-ace66ab659b2"
/dev/nvme0n1p5: PARTLABEL="L2ARC" PARTUUID="60c563fc-91f8-4ec4-afc0-b7794c63f31c"
 
zpool add rpool cache 60c563fc-91f8-4ec4-afc0-b7794c63f31c
zpool add rpool log d6da74cd-32e7-4286-8e78-ace66ab659b2
zpool status
  pool: rpool
 state: ONLINE
  scan: scrub repaired 0B in 0 days 00:11:23 with 0 errors on Sun May 10 00:35:24 2020
config:
 
	NAME                                    STATE     READ WRITE CKSUM
	rpool                                   ONLINE       0     0     0
	  sda                                   ONLINE       0     0     0
	logs	
	  d6da74cd-32e7-4286-8e78-ace66ab659b2  ONLINE       0     0     0
	cache
	  60c563fc-91f8-4ec4-afc0-b7794c63f31c  ONLINE       0     0     0
 
zpool iostat -v 1

zfs destroy rpool/data

For nodes without local-zfs, i.e. Debian based custom system it is possible to add local-zfs storage later.

zpool create -f -o ashift=12 rpool /dev/sdb
zfs set compression=lz4 rpool
zfs create rpool/data
 
# You can get a list of available ZFS filesystems with:
pvesm zfsscan
 
zpool status -v
zfs list

Datacenter –> Storage –> local-zfs

• Disable node restriction