ZFS stands for Zettabyte File system and to save you a lot of boring reading it is a file system which protects agains data corruption provide high redundancy and high availability. It was designed by Sun Microsystems and there are two implementations in nutshell:

• Oracle ZFS
• OpenProject ZFS

Both implementations are pretty close to each other and both are widely used in the IT world to provide availability FS with high protection and performance. ZFS is native to Oracle NAS Storage Appliance. With ZFS you can create a pool which you can share with out appliances through either NFS or Samba.

So let's create one pool:

We can create a pool, using the zfs command line as follows:

We all likes pools, especially with water and diving equipment. But let's create a ZPool now in RAID 2 with 10 disks and name it…..“tank” :)

Create a pool

[root@hostname ~]# zpool create tank -O casesensitivity=mixed -O compression=lz4 raidz2 disk1 disk2 disk3 disk4 disk5 disk6 disk7 disk8 disk9 disk10 -f

The following command, will create you a pool comprised by 10 disks in raid-5 configuration with double parity. The pool name is called: “tank” and with compression lz4. You can choose one of these compression algorithms by the way :)

• On
• Off
• lzjb
• gzip
• gzip[1-9]
• zle
• lz4 ← The one used here and it is pretty good

You can also list the status of the created pool as follows:

Pool status

[root@hostname ~]# zpool list -v
NAME   SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
tank  9.06T  1.94T  7.12T         -     4%    21%  1.00x  ONLINE  -
  raidz2  9.06T  1.94T  7.12T         -     4%    21%
    disk1      -      -      -         -      -      -
    disk2      -      -      -         -      -      -
    disk3      -      -      -         -      -      -
    disk4      -      -      -         -      -      -
    disk5      -      -      -         -      -      -
    disk6      -      -      -         -      -      -
    disk7      -      -      -         -      -      -
    disk8      -      -      -         -      -      -
    disk9      -      -      -         -      -      -
    disk10      -      -      -         -      -      -

If you are worried about the integrity of the pool, you can of course perform integrity check and verify the data corruption as follows:

Check Integrity

[root@hostname ~]# zpool scrub tank
[root@hostname ~]# zpool status
  pool: tank
 state: ONLINE
  scan: scrub repaired 0B in 0h56m with 0 errors on Mon Aug 12 12:40:46 2019
config:
 
        NAME        STATE     READ WRITE CKSUM
        tank        ONLINE       0     0     0
          raidz2-0  ONLINE       0     0     0
            disk1   ONLINE       0     0     0
            disk2   ONLINE       0     0     0
            disk3   ONLINE       0     0     0
            disk4   ONLINE       0     0     0
            disk5   ONLINE       0     0     0
            disk6   ONLINE       0     0     0
            disk7   ONLINE       0     0     0
            disk8   ONLINE       0     0     0
            disk9   ONLINE       0     0     0
            disk10  ONLINE       0     0     0
 
errors: No known data errors
 
 
P.S. you can stop the scrubbing with: zpool scrub -s tank
[root@hostname ~]# zpool scrub -s tank

After we have a pool, we can create a ZFS file system on it :)

The ZFS will be shared either over SMB (Samba) or NFS(Network File system) to other machines. NFS is great way to setup Oracle RAC (with Direct NFS of course) and Samba is great way for a backup solution.

So let's create NFS :)

The command is fairly simple:

Create ZFS File system

[root@hostname ~]# zfs create tank/backup

We can create also multiple aggregation of that file system, for example:

Create Accumulative ZFS File system

[root@hostname ~]# zfs create tank/backup/servers/server_name

You can check the status of the file systems as well, very easy, as follows:

List ZFS File Systems

[root@hostname ~]# zfs list
NAME                          USED  AVAIL  REFER  MOUNTPOINT
tank                         1.55T  5.45T  50.2K  /tank
tank/backup                  1.55T  5.45T  52.6K  /tank/backup
tank/backup/zfsForServerOne    46.4G  5.45T  46.4G  /tank/backup/forServerOne
tank/backup/zfsForServerTwo  1.50T  5.45T  1.50T  /tank/backup/forServerTwo

We can see that the total availability is 5.45 TBs, our of which are used: 1.55 TBs. 46.4 GBs on the file system for the first server and 1.5 TBs on the file system for the 2nd server.

We spoke, a lot about sharing and giving and stuff like that, but HOW we share of ZFS file system. So let's check it out :)

In the past, sharing of the NFS was done via the following commands:

Old way of sharing ZFS as NFS

[root@hostname ~]# share -F nfs /tank
[root@hostname ~]# cat /etc/dfs/sharetab
/tank    -       nfs     rw

That is the old way, so how is the new way. Well, we have to set who server can do what :) For example:

New way of Sharing ZFS as NFS

[root@hostname ~]# zfs set sharenfs="rw=@serverOne/16,ro=@serverTwo/28" tank/backup/zfsForServerOne

What that does is:

• Give READ-WRITE access of ZFS: tank/backup/zfsForServerOne to Server One's IP with netmask: 16
• Give READ-ONLY access of ZFS: tank/backup/zfsForServerOne to Server Two's IP with netmask: 28

It is uselessly to say that the NFS port (111) should be allowed both ways :)

For example: server_one (111) ↔ (111) Oracle_NAS_Server (111) ↔ (111) server_two

Of course, such configuration (with READ-ONLY) isn't suitable for RAC, if you don't want to hit your head in the wall long time. If you wish, to do so, please go ahead and try to install RAC on that :)

That command will update also the sharetab file of course:

Check the sharing settings

[root@tbp-slm-zfs01 ~]# cat /etc/dfs/sharetab
/tank/backup/zfsForServerOne    -       nfs     rw=@serverOne/16,ro=@serverTwo/28

After you start the NFS server on the Oracle NAS, you can try to mount it on serverOne and serverTwo. I will not cover this as I have done in other section, but it will look like a normal NFS:

NFS on serverOne

[root@serverOne]# df
Filesystem                                 1K-blocks       Used  Available Use% Mounted on
devtmpfs                                     3985372          0    3985372   0% /dev
tmpfs                                        4000116          0    4000116   0% /dev/shm
tmpfs                                        4000116      33480    3966636   1% /run
tmpfs                                        4000116          0    4000116   0% /sys/fs/cgroup
/dev/mapper/volGroup-root                   38774276    2454892   36319384   7% /
/dev/sda1                                     999320     181048     749460  20% /boot
tmpfs                                         800020          0     800020   0% /run/user/283600015
/dev/mapper/vg_mongo-lv_mongo              721426424  277759688  409058372  41% /app/data
172.23.4.101:/tank/backup/zfsForServerOne 7463166976 1611866112 5851300864  22% /apphome/backup

Cheers and enjoy :)

For more info you can check here :) Compression Algorithms