A friend of mine likes to try ZFS on CentOS 7, therefore I decide to make a guide for him. The following instructions have been well tested on CentOS 7.<\/p>\n
Before you decide to put ZFS in a production use, you should be aware of the following:<\/p>\n
By default, ZFS is not available in the standard CentOS repository. We will need to include some 3rd party repositories here.<\/p>\n
\r\nsudo rpm -Uvh http:\/\/www.elrepo.org\/elrepo-release-7.0-2.el7.elrepo.noarch.rpm\r\nsudo rpm -Uvh http:\/\/dl.fedoraproject.org\/pub\/epel\/epel-release-latest-7.noarch.rpm\r\nsudo rpm -Uvh https:\/\/forensics.cert.org\/cert-forensics-tools-release-el7.rpm\r\nsudo rpm -Uvh http:\/\/download.zfsonlinux.org\/epel\/zfs-release.el7_6.noarch.rpm\r\n\r\nsudo yum update -y\r\nsudo yum groupinstall -y \"Development Tools\" \"Development Libraries\" \"Additional Development\"\r\nsudo yum install -y kernel-devel kernel-headers\r\n<\/pre>\nIt is very likely that the system will install a new kernel. You may want to reboot the computer before installing the ZFS.<\/p>\n
\r\nsudo reboot\r\n<\/pre>\nPlease make sure that the system does not update automatically. If you need to update the system, please exclude the kernel and related modules from the update.<\/p>\n
\r\nsudo nano \/etc\/yum.conf \r\nexclude=kernel*\r\n<\/pre>\nNow you are on the latest kernel. Let’s install the ZFS:<\/p>\n
\r\nsudo yum install -y zfs\r\nsudo \/sbin\/modprobe zfs\r\n<\/pre>\nNow, you can create a simple stripped ZFS. Stripped ZFS gives you the best performances and zero data protections. When referencing the disks, we don’t want to use \/dev\/sd*, instead, we want to use the device id directly, e.g., \/dev\/disk\/by-id\/wwn-0x8000c8004e8ac11a<\/p>\n
\r\nls \/dev\/disk\/by-id\/\r\n\r\n\r\nlrwxrwxrwx 1 root root 9 Jan 3 21:49 wwn-0x8000c8004e8ac11a -> ..\/..\/sde\r\nlrwxrwxrwx 1 root root 9 Jan 3 21:49 wwn-0x8000c8008ad0a22d -> ..\/..\/sdd\r\nlrwxrwxrwx 1 root root 9 Jan 3 21:49 wwn-0x8000c8008b4f6338 -> ..\/..\/sda\r\nlrwxrwxrwx 1 root root 9 Jan 3 21:49 wwn-0x8000c8008b52144c -> ..\/..\/sdc\r\nlrwxrwxrwx 1 root root 9 Jan 3 21:49 wwn-0x8000c8008b59a553 -> ..\/..\/sdb\r\n<\/pre>\nOnce you identify the list of the hard disks, we can create a simple stripped ZFS. This will create a ZFS under \/storage<\/strong>. You can replace storage<\/strong> to anything you like.<\/p>\n
\r\n#We are going to create a ZFS pool with three disks. You can add more if you like. For stripped design, the higher number of disks, the faster the IO speed.\r\nzpool create -f storage \/dev\/disk\/by-id\/device1 \/dev\/disk\/by-id\/device2 \/dev\/disk\/by-id\/device3 \r\n<\/pre>\nstorage is like a big umbrella. Under this umbrella, we will need to create multiple “partitions” for storing data.<\/p>\n
\r\nzfs create storage\/mydata\r\n<\/pre>\nIf you have a fast CPU like i7, you may want to turn on the compression. This will reduce the amount of data write to the system, and it will improve the overall performance.<\/p>\n
\r\nsudo zfs set compression=lz4 storage\r\n<\/pre>\nFinally we want to change the ownership and the permissions<\/p>\n
\r\n#Assuming that you are part of the wheel group\r\nsudo chown -R root:wheel \/storage\r\nsudo chmod -R g+rw \/storage\r\n<\/pre>\nNow, run df and you should be able to see the ZFS in your system.<\/p>\n
\r\n#df -h\r\nFilesystem Size Used Avail Use% Mounted on\r\nstorage 6.8T 128K 6.8T 1% \/storage\r\nstorage\/mydata 13T 6.1T 6.8T 48% \/storage\/mydata\r\n<\/pre>\nYou can monitor the health of the ZFS system.<\/p>\n
\r\n#sudo zpool status\r\n\r\n\r\n\r\n pool: storage\r\n state: ONLINE\r\nconfig:\r\n\r\n NAME STATE READ WRITE CKSUM\r\n storage ONLINE 0 0 0\r\n wwn-0x8000c8004e8ac11a ONLINE 0 0 0\r\n wwn-0x8000c8008ad0a22d ONLINE 0 0 0\r\n wwn-0x8000c8008b4f6338 ONLINE 0 0 0\r\n wwn-0x8000c8008b52144c ONLINE 0 0 0\r\n\r\n\r\nerrors: No known data errors\r\n<\/pre>\nFor some very odd reasons, ZFS will not be loaded automatically. We want to make sure that ZFS will be loaded after reboot.<\/p>\n
\r\n#sudo nano \/etc\/crontab\r\n\r\n#Add the following:\r\n@reboot root sleep 10; zpool import -a;\r\n<\/pre>\nNow you can try to test the ZFS by running dd or copying a big file to the ZFS. If you are not happy with the configurations, you can always destroy it and re-create the ZFS again.<\/p>\n
\r\nsudo zpool destroy storage\r\n<\/pre>\nFurther Reading<\/h2>\n
\n
- Running ZFS on Linux: Things you should know and be aware of<\/a><\/li>\n
- ZFS Performance: Mirror VS RAIDZ VS RAIDZ2 vs RAIDZ3 vs Striped<\/a><\/li>\n
- How to fix ZFS after updating to a newer kernel<\/a><\/li>\n
- How to improve ZFS performance<\/a><\/li>\n<\/ul>\n
Have fun!<\/p>\n
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