© Damian Wojsław 2017

Damian Wojsław, Introducing ZFS on Linux, https://doi.org/10.1007/978-1-4842-3306-1_3

3. Installation

Damian Wojsław1 

(1)ul. Duńska 27i/8, Szczecin, 71-795 Zachodniopomorskie, Poland

This chapter goes through the basic installation of ZFS modules in your Linux distribution of choice. Ubuntu allows for quick install and setup, so we are going to use it as an example.

System Packages

Before going any further, you need to install some packages from the standard distribution repositories.

Virtual Machine

Before buying the hardware and running tests on bare metal, you may want to install and test ZFS within a virtual machine . It is a good idea and I encourage you to do so. You may, in a very simple and efficient way, get used to administering ZFS pools. You may also check which distribution works better for you. There are no requirements to the virtualization engine. You can use VirtualBox, VMware, KVM, Xen, or any other VM you feel comfortable with. Keep in mind that the tool you use should be able to provide your guest machine with virtual disks to play with. While you can create a pool on the files created within the VM, I don’t recommend that way of testing it.

Note

Bear in mind that virtual machines are not suitable for performance testing. Too many factors stand in the way of reliable results.

Ubuntu Server

If, for some reason, you are running Ubuntu prior to 15.10, you will need to add a special PPA repository:

trochej@ubuntuzfs:~$ sudo add-apt-repository ppa:zfs-native/stable

[sudo] password for trochej:
 The native ZFS filesystem for Linux. Install the ubuntu-zfs package.

Please join this Launchpad user group if you want to show support for ZoL:

  https://launchpad.net/~zfs-native-users

Send feedback or requests for help to this email list:

  http://list.zfsonlinux.org/mailman/listinfo/zfs-discuss

Report bugs at:

  https://github.com/zfsonlinux/zfs/issues  (for the driver itself)
  https://github.com/zfsonlinux/pkg-zfs/issues (for the packaging)

The ZoL project home page is:

  http://zfsonlinux.org/
 More info: https://launchpad.net/~zfs-native/+archive/ubuntu/stable
Press [ENTER] to continue or ctrl-c to cancel adding it

gpg: keyring `/tmp/tmp4_wvpmaf/secring.gpg' created
gpg: keyring `/tmp/tmp4_wvpmaf/pubring.gpg' created
gpg: requesting key F6B0FC61 from hkp server keyserver.ubuntu.com
gpg: /tmp/tmp4_wvpmaf/trustdb.gpg: trustdb created
gpg: key F6B0FC61: public key "Launchpad PPA for Native ZFS for Linux" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)
OK

With Ubuntu 15.10 and later, ZFS support packages are already included in the standard repository. You will need to install the following packages :

trochej@ubuntuzfs:~$ sudo apt-get install zfsutils-linux

This will compile the appropriate kernel modules for you. You can later confirm that they were built and in fact loaded by running lsmod:

trochej@ubuntuzfs:~$ sudo lsmod | grep zfs

zfs                  2252800  0
zunicode              331776  1 zfs
zcommon                53248  1 zfs
znvpair                90112  2 zfs,zcommon
spl                   102400  3 zfs,zcommon,znvpair
zavl                   16384  1 zfs

You should be now able to create a pool:

trochej@ubuntuzfs:~$ sudo zpool create -f datapool 
    mirror /dev/sdb /dev/sdc 
    mirror /dev/sdd /dev/sde 
    mirror /dev/sdf /dev/sdg

trochej@ubuntuzfs:~$ sudo zpool status
  pool: datapool
 state: ONLINE
  scan: none requested
 config:

    NAME        STATE     READ WRITE CKSUM
    datapool    ONLINE       0     0     0
      mirror-0  ONLINE       0     0     0
        sdb     ONLINE       0     0     0
        sdc     ONLINE       0     0     0
      mirror-1  ONLINE       0     0     0
        sdd     ONLINE       0     0     0
        sde     ONLINE       0     0     0
      mirror-2  ONLINE       0     0     0
        sdf     ONLINE       0     0     0
        sdg     ONLINE       0     0     0

errors: No known data errors

There is another package you will want to install:

trochej@ubuntuzfs:~$ sudo apt-get install zfs-zed

zed is a ZFS Event Daemon. It is a daemon service that will listen to any ZFS-generated kernel event. It’s explained in more detail in the next section.

CentOS

You will need a system information tool that is not installed by default for monitoring, troubleshooting, and testing your setup:

[root@localhost ~]# yum install sysstat

Contrary to Ubuntu, CentOS doesn’t have ZFS packages by default in the repository, neither in its 6.7 nor 7 version. Thus you need to follow the directions here: http://zfsonlinux.org/epel.html .

The installation for CentOS 7 is exactly the same, except for the package names:

[root@CentosZFS ~]# yum localinstall --nogpgcheck https://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
[root@CentosZFS ~]# yum localinstall --nogpgcheck http://archive.zfsonlinux.org/epel/zfs-release.el6.noarch.rpm
[root@CentosZFS ~]# yum install -y kernel-devel zfs

After some time, you should be ready to probe and use ZFS modules:

[root@CentosZFS ~]# modprobe zfs
[root@CentosZFS ~]# lsmod | grep zfs
zfs                  2735595  0
zcommon                48128  1 zfs
znvpair                80220  2 zfs,zcommon
spl                    90378  3 zfs,zcommon,znvpair
zavl                    7215  1 zfs
zunicode              323046  1 zfs

You’re now ready to create a pool on your attached disks:

[root@CentosZFS ~]# zpool create -f datapool mirror /dev/sdb /dev/sdc mirror /dev/sdd /dev/sde
[root@CentosZFS ~]# zpool status
  pool: datapool
 state: ONLINE
  scan: none requested
 config:

    NAME        STATE     READ WRITE CKSUM
    datapool    ONLINE       0     0     0
      mirror-0  ONLINE       0     0     0
        sdb     ONLINE       0     0     0
        sdc     ONLINE       0     0     0
      mirror-1  ONLINE       0     0     0
        sdd     ONLINE       0     0     0
        sde     ONLINE       0     0     0

errors: No known data errors

This code installed the aforementioned ZED for you.

System Tools

You will need some system tools . Get used to them.

  • smartctl: The smartmontools package contains two utility programs (smartctl and smartd) to control and monitor storage systems. It uses the Self-Monitoring, Analysis, and Reporting Technology System (SMART) built into most modern ATA/SATA, SCSI/SAS, and NVMe disks.

  • lsblk: Tells you what block devices you have. It will assist you in identifying the drive names you will use while setting your ZFS pool.

  • blkid: Helps you identify drives already used by other file systems. You may want to use mount and df for that purpose too.

ZED

As mentioned, zed is a daemon that will listen to kernel events related to ZFS. Upon receiving events, it will conduct any action defined in so-called ZEDLETs —a script or program that will carry on whatever action it’s supposed to do. ZED is a Linux-specific daemon. In illumos distributions, FMA is the layer responsible for carrying out corrective actions.

Writing ZEDLETs is a topic beyond this guide, but the daemon is essential for two important tasks: monitoring and reporting (via mail) pool health and replacing failed drives with hot spares.

Even though it is a ZFS that is responsible for marking a drive as faulty, the replacement action needs to be carried out by a separate entity.

For those actions to work , after installing the daemon, open its configuration file. It’s usually found in /etc/zfs/zed.d/zed.rc:

# zed.rc                

# Absolute path to the debug output file.                
# ZED_DEBUG_LOG="/tmp/zed.debug.log"                

# Email address of the zpool administrator.                
#   Email will only be sent if ZED_EMAIL is defined.                
ZED_EMAIL="[email protected]"

# Email verbosity.                
#   If set to 0, suppress email if the pool is healthy.                
#   If set to 1, send email regardless of pool health.                
#ZED_EMAIL_VERBOSE=0                

# Minimum number of seconds between emails sent for a similar event.                
#ZED_EMAIL_INTERVAL_SECS="3600"                

# Default directory for zed lock files.                
#ZED_LOCKDIR="/var/lock"                

# Default directory for zed state files.                
#ZED_RUNDIR="/var/run"                

# The syslog priority (eg, specified as a "facility.level" pair).                
ZED_SYSLOG_PRIORITY="daemon.notice"

# The syslog tag for marking zed events.                
ZED_SYSLOG_TAG="zed"

# Replace a device with a hot spare after N I/O errors are detected.                
#ZED_SPARE_ON_IO_ERRORS=1                

# Replace a device with a hot spare after N checksum errors are detected.                
#ZED_SPARE_ON_CHECKSUM_ERRORS=10

Notice ZED_EMAIL, ZED_SPARE_ON_IO_ERRORS, and ZED_SPARE_ON_CHECKSUM_ERRORS. Uncomment them if you want this functionality.

You can view the kernel messages that zed will listen to by using zpool events with or without the -v switch. Without the switch, you will receive a list similar to this one:

trochej@ubuntuzfs:~$ sudo zpool events
TIME                           CLASS
Feb 15 2016 17:43:08.213103724 resource.fs.zfs.statechange
Feb 15 2016 17:43:08.221103592 resource.fs.zfs.statechange
Feb 15 2016 17:43:08.221103592 resource.fs.zfs.statechange
Feb 15 2016 17:43:08.661096327 ereport.fs.zfs.config.sync
Feb 15 2016 18:07:39.521832629 ereport.fs.zfs.zpool.destroy

Those should be pretty obvious and, in this case, it’s directly related to creation, import, and destruction of a pool.

With the -v switch, the output is more verbose:

trochej@ubuntuzfs:~$ sudo zpool events -v
TIME                           CLASS
Feb 15 2016 17:43:08.213103724 resource.fs.zfs.statechange
    version = 0x0
    class = "resource.fs.zfs.statechange"
    pool_guid = 0xa5c256340cb6bcbc
    pool_context = 0x0
    vdev_guid = 0xba85b9116783d317
    vdev_state = 0x7
    time = 0x56c2001c 0xcb3b46c
    eid = 0xa

Feb 15 2016 17:43:08.213103724 resource.fs.zfs.statechange
    version = 0x0
    class = "resource.fs.zfs.statechange"
    pool_guid = 0xa5c256340cb6bcbc
    pool_context = 0x0
    vdev_guid = 0xbcb660041118eb95
    vdev_state = 0x7
    time = 0x56c2001c 0xcb3b46c
    eid = 0xb
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