![]() In the event of any corruption, the additional copies help safe guard against data loss. For important data, you may specify additional copies of the data to be written. copies=N, where N is the number of copies.Other ashift values will be covered below. For disks with advanced format (AF) where sector sizes are 4K, you must adjust the ashift=12 property manually to avoid performance degradation. Some pool properties can only be set when it is first created. Using the disk names such as /dev/sdx is not reliable as the naming can change when udev rules are changed which can potentially prevent your pool from importing properly on startup. In fact, it's a recommendation made by the ZoL project. When specifying the device on Linux, it's recommended to use disk IDs. POOL_TYPE + DISK - one or more vdev configuration.-d - Do not enable any features unless specified.-n - Display creation but don't create pool.You may only grow a raidz by replacing each storage device with a larger capacity.Ĭreate a zpool and its corresponding vdevs using the zpool create command.You may not add additional devices to a raidz to expand it.You can only destroy and re-create a vdev with a smaller size. ![]() Virtual devices in ZFS have some limitations you must keep in mind: log - A device for ZFS Intent Log (ZIL), more on this later.cache - A device used for level 2 adaptive read cache (L2ARC), more on this later.You must enable a setting for it to be dynamically added to a failed vdev, which is disabled by default. spare - A hot-spare that can be used as a temporary replacement.The number represents how many disk failures can be tolerated. raidz1/2/3 - similar to a RAID 5 or RAID 6.Read performance is excellent since data can be retrieved from all storage devices simultaneously. A mirror can survive any failure so long as at least one device remains healthy. mirror - similar to a RAID 1 where all blocks are mirrored across all devices, providing high performance and fault tolerance.file - An absolute path to a disk image.Beware that there is no redundancy or fault tolerance. The capacity of the vdev is the sum of all underlying devices. device - One or more physical disk or partition on the system.The concept of a virtual device or vdev encapsulates one or more physical storage device. See: ttps://When creating a zpool, the virtual device configuration must be given. As a consequence, a failure of any member vdev will result in the failure of the zpool.Īs a side note, recovery of data from a simple zpool is unlike that of a JBOD due to how data is evenly distributed on all vdevs. Within a zpool, ZFS treats all member vdevs similar to disks in a JBOD but distributes data evenly. They act like volumes but act like an already formatted filesystem and can be mounted to a mount point on the system.Ī zpool contains one or more vdevs in any configuration. It treats all vdevs like a JOBD and distributes data depending on factors such as load and utilization. A vdev represents one or more devices in ZFS and employs one of five parity methods: single device, mirror, RAIDz1, RAIDz2, RAIDz3.It can be a SSD, traditional HDD, or even a file. A device can be any block device installed on the system.$ gpg -keyserver -recv-keys 4F3BA9AB6D1F8D683DC2DFB56AD860EED4598027Ī few fundamental concepts to understand when using ZFS are: devices, vdevs, zpools, and datasets.
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