SOLVED Extend A Raidz volume x1 HDD

[ferroresonance]

Hi All , firstly my apologies is this thread is duplicate of a question some one else has asked

Hardware:
HP proliant n54l, 16GB Ram 5x 3TB Seagate Barracuda drives setup in Raidz.

FreeNAS Version and build:
FreeNAS-9.10.1-U2 (f045a8b)

FreeNAS Volume and Data Set:
1x Volume using 5x 3TB split into 3 Data sets as windows share

Question:
I would like to add 1 more 3TB Seagate Barracuda to my existing Raidz volume, is it possible to add the extra drive and just extend the volume? I have read the guide and it basically says if you want to extend a 3 drive raidz i will need to add another 3 drives????

 

[Stux]

You can't extend a raidz volume.

You can replace all the drives with larger ones. Not recommended.

Or you can add another set of drives. Not recommended.

Or you can backup your data. Recreate the volume as raidz/Raidz2 with more drives, and restore.

You should look into why raidz1 is not recommended.

 

[{HD}]

You read the Docs correctly.

• add additional disks to increase the capacity of the ZFS pool. The caveats to doing this are described below.

When adding disks to increase the capacity of a volume, ZFS supports the addition of virtual devices, known as vdevs, to an existing ZFS pool. A vdev can be a single disk, a stripe, a mirror, a RAIDZ1, RAIDZ2, or a RAIDZ3. After a vdev is created, more drives cannot be added to that vdev; however, you can stripe a new vdev (and its disks) with another of the same type of existing vdev to increase the overall size of ZFS the pool. In other words, when you extend a ZFS volume, you are really striping similar vdevs. Here are some examples:

• to extend a ZFS stripe, add one or more disks. Since there is no redundancy, you do not have to add the same amount of disks as the existing stripe.
• to extend a ZFS mirror, add the same number of drives. The resulting striped mirror is a RAID 10. For example, if you have 10 drives, you could start by creating a mirror of two drives, extending this mirror by creating another mirror of two drives, and repeating three more times until all 10 drives have been added.
• to extend a three drive RAIDZ1, add three additional drives. The result is a RAIDZ+0, similar to RAID 50 on a hardware controller.
• to extend a RAIDZ2 requires a minimum of four additional drives. The result is a RAIDZ2+0, similar to RAID 60 on a hardware controller.

If you try to add an incorrect number of disks to the existing vdev, an error message will appear, indicating the number of disks that are needed. You will need to select the correct number of disks in order to continue.

One of many posts on why to avoid z1:
https://forums.freenas.org/index.php?threads/for-the-people-thinking-about-raidz1.45592/
The jist is: When you replace a failed hard drive the new drive needs to be rebuilt or 'resilvered'. The resilvering process puts significant stress on the other drives. If this stress causes another drive to fail then your data is DEAD FOREVER.

Or you can backup your data. Recreate the volume as raidz/Raidz2 with more drives, and restore

This is exactly what I would do except go for raid z2 at the least.

 

[ferroresonance]

Hi Stux/{HD}
Thanks for the prompt reply, bit of a pity that that cant be done but i am sure there is a engineering reason. In regards to running in Raidz as opposed to other raid options, I under stand that the recommendations push towards raidz2 or raidz3 but i am really not that concerned if 1 drive fails and during the re silvering another drive fails and i lose all my data, as i never store all my data in one location its just best practice. If that happened i would rebuild with new drives and recopy all the data back. I run Raidz to give me some protection with better performance than the other Raidz2/3. If the re silvering was successful then fantastic, but i would then start to replace the old drives with new.

 

[{HD}]

...i am really not that concerned if 1 drive fails and during the re silvering another drive fails and i lose all my data, as i never store all my data in one location its just best practice.

If that is true, then just do what everyone says NOT to do and add a vdev of 1 stripped disk to your pool. This will make it so that if that one drive fails then you have total loss but, if one of the other drives fail your still in z1.

 

[ferroresonance]

Hi HD, at this point my direction is to destroy the volume and rebuild as raidz, maybe raidz2 (less pain restoring all data over 2 days) . I will sleep on the option of z2 and consider spending the extra $140


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