add some basic explanation how ZFS dRAID works including links to openZFS for more details
add documentation for two dRAID parameters used in code Signed-off-by: Stefan Hrdlicka <s.hrdli...@proxmox.com> --- local-zfs.adoc | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/local-zfs.adoc b/local-zfs.adoc index ab0f6ad..a424bbd 100644 --- a/local-zfs.adoc +++ b/local-zfs.adoc @@ -32,7 +32,8 @@ management. * Copy-on-write clone -* Various raid levels: RAID0, RAID1, RAID10, RAIDZ-1, RAIDZ-2 and RAIDZ-3 +* Various raid levels: RAID0, RAID1, RAID10, RAIDZ-1, RAIDZ-2, RAIDZ-3, +dRAID, dRAID2, dRAID3 * Can use SSD for cache @@ -244,6 +245,44 @@ them, unless your environment has specific needs and characteristics where RAIDZ performance characteristics are acceptable. +ZFS dRAID +~~~~~~~~~ + +In a ZFS dRAID (declustered RAID) the hot spare drive(s) participate in the RAID. +Their spare capacity is reserved and used for rebuilding when one drive fails. +This provides, depending on the configuration, faster rebuilding compared to a +RAIDZ in case of drive failure. More information can be found in the official +OpenZFS documentation. footnote:[OpenZFS dRAID +https://openzfs.github.io/openzfs-docs/Basic%20Concepts/dRAID%20Howto.html] + +NOTE: dRAID is intended for more than 10-15 disks in a dRAID. A RAIDZ +setup should be better for a lower amount of disks in most use cases. + + * `dRAID1` or `dRAID`: requires at least 2 disks, one can fail before data is +lost + * `dRAID2`: requires at least 3 disks, two can fail before data is lost + * `dRAID3`: requires at least 4 disks, three can fail before data is lost + + +Additional information can be found on the manual page: + +---- +# man zpoolconcepts +---- + +Spares and Data +^^^^^^^^^^^^^^^ +The number of `spares` tells the system how many disks it should keep ready in +case of a disk failure. The default value is 0 `spares`. Without spares, +rebuilding won't get any speed benefits. + +`data` defines the number of devices in a redundancy group. The default value is +8. Except when `disks - parity - spares` equal something less than 8, the lower +number is used. In general, a smaller number of `data` devices leads to higher +IOPS, better compression ratios and faster resilvering, but defining fewer data +devices reduces the available storage capacity of the pool. + + Bootloader ~~~~~~~~~~ -- 2.30.2 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
