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--- zfs:add_a_mirror_to_an_existing_zfs_drive [2020/06/15 22:10] – peter
+++ zfs:add_a_mirror_to_an_existing_zfs_drive [2021/10/13 22:27] (current) – removed peter
@@ Line 1: / Line 1: @@
-====== ZFS - Add a Mirror to an Existing ZFS Drive ======
-Convert the most basic ZFS pool, a system with a single disk, to a Mirror or Stripe.
-Current Setup:
-  * We have a single disk attached to our system, **/dev/da1**
-  * This disk is used as a simple zfs pool, **tank**
-  * You bought another disk and want to mirror the pool to the new disk, **/dev/da2**
-----
-===== Ensure the disk names are correct =====
-Make sure you’ve got the disk names correct.
-Use **dmesg** to see the system messages, to determine which disk is which.
-<WRAP alert>
-**ALERT:**  This can be dangerous if you use the wrong disk, as it will destroy all data on the selected disk.
-</WRAP>
-----
-===== Prepare Your Drive =====
-Delete any existing partitions if needed.
-<code bash>
-sudo gpart destroy -F /dev/da2
-</code>
-Format the drive as gpt:
-<code bash>
-sudo gpart create -s gpt /dev/da2
-</code>
-Create a zfs partition:
-<code bash>
-sudo gpart add -t freebsd-zfs /dev/da2
-</code>
-This new partition is **/dev/da2p1**, and will nbe added to the existing partition next.
-----
-===== Get the Partition IDs =====
-Get the information needed to feed to zfs so that it will configure the drives correctly.
-We will need the gpt ID of the existing partition as well as the new one we’re adding.
-The **zpool status** command will show all we need to know about the existing drive, partition, and pool.
-<code bash>
-zpool status
-</code>
-returns:
-<code bash>
-  pool: Internal
- state: ONLINE
-  scan: none requested
-config:
-        NAME                                          STATE     READ WRITE CKSUM
-        Tank                                          ONLINE       0     0     0
-          gptid/799a169a-aa2f-11ea-bfaa-00d861fcb7d8  ONLINE       0     0     0
-errors: No known data errors
-</code>
-<WRAP info>
-**NOTE:**  The bit after “gptid/” is the unique ID of our existing zfs disk: **799a169a-aa2f-11ea-bfaa-00d861fcb7d8**.
-</WRAP>
-Determine the ID of the new partition we just created.
-Here’s an abbreviated output of **gpart list**:
-<code bash>
-gpart list
-</code>
-returns:
-<code bash>
-Geom name: da2
-modified: false
-state: OK
-fwheads: 255
-fwsectors: 63
-last: 7814037127
-first: 40
-entries: 128
-scheme: GPT
-Providers:
-. Name: da2p1
-   Mediasize: 4000786984960 (3.6T)
-   Sectorsize: 512
-   Stripesize: 4096
-   Stripeoffset: 0
-   Mode: r0w0e0
-   rawuuid: 8229a169a-aa2f-11ea-bfaa-00d861fcb7d8
-   rawtype: 5539a169a-aa2f-11ea-bfaa-00d861fcb7d8
-   label: (null)
-   length: 4000786984960
-   offset: 20480
-   type: freebsd-zfs
-   index: 1
-   end: 7814037119
-   start: 40
-Consumers:
-. Name: da2
-   Mediasize: 4000787029504 (3.6T)
-   Sectorsize: 512
-   Stripesize: 4096
-   Stripeoffset: 0
-   Mode: r0w0e0
-....
-</code>
-<WRAP info>
-**NOTE:**  The **rawuuid** is what is needed, in this example, this is **8229a169a-aa2f-11ea-bfaa-00d861fcb7d8**.
-</WRAP>
-----
-===== Mirror the disks =====
-Tell zfs that these two disks need to be joined together as a mirrored set.
-Here are the inputs:
-    The pool name: Tank
-    The existing partition uuid: 799a169a-aa2f-11ea-bfaa-00d861fcb7d8
-    The new partition uuid: 8229a169a-aa2f-11ea-bfaa-00d861fcb7d8
-Mirror the disks:
-<code bash>
-sudo zpool attach Tank /dev/gptid/799a169a-aa2f-11ea-bfaa-00d861fcb7d8 /dev/gptid/8229a169a-aa2f-11ea-bfaa-00d861fcb7d8
-</code>
-ZFS will attach the new partition to the existing drive set, mirroring all data from the old drive to the new one.
-<WRAP info>
-**NOTE:**  This process of copying data (“resilvering” in zfs parlance) will take a while.
-You can use the “zpool status Tank” command to see the progress, including an estimated time of completion.
-With two 4 TB drives containing a little over 1 TB of data) it took about 3 hours.
-</WRAP>
-<WRAP info>
-**NOTE:**  **zpool attach** can only add mirrors to an existing zpool device.
-You can’t mess with RAID-Z sets in this manner, even though that would be much more useful.
-</WRAP>
-----