System building

[Ophidio]

I'm still developing my new system, I'm a newbie on FreeNAS so some confusion. I'm thinking about which configuration use and I'm oriented to a raid 1+0. So i think to create 2 vdevs each with 2 disks mirrored and join them together into one zpool. Here come my problem, maybe I use 4 drive each 2tb so 4 tb space available. When this space was over can i change only 2 disk from the same vdev (one at time) and expand my zpool available space? Ie. I change 2 disk from vdev1, with 2 hdd 3tb each, can I expand the zpool so to use the 1tb free space?



Thank you

 

[darkwarrior]

Hello there,

for your information: What you describe as RAID1+0 is not proper ZFS terminology, but is being referred to as Striped Mirrors.
And yes, when you will replace the 2TB disks with 3TB disks each VDEV will expand and give you 1TB (minus ZFS overhead) of free space. :)
You can take a look at @Bidule0hm's Calculator to get an idea of the actual real space you will have available on your FreeNAS server ;)

 

[Ophidio]

Thank you. I'm sorry about the term, but i'm new on this system so still old school!!!!

 

[darkwarrior]

No problem, you're welcome. ;)
We are all learning new things every day :D

You might want to read through the resources below as they give very useful information about ZFS:
Terminology and Abbreviations | Cyberjock's ZFS Guide | Hardware Recommendations | RAID-Z1/RAID5 isn't recommended

 

[wblock]

The last one is misleading. RAIDZ1 is not exactly RAID5.

 

[darkwarrior]

The last one is misleading. RAIDZ1 is not exactly RAID5.

Technically, you are right.
The post itself is more about the fact that single-disk-parity VDEVs (hence the comparison RAIDZ1//RAID5) are not recommended to be used with disks larger than 1TB. :D

 

[Ophidio]

Technically, you are right.
The post itself is more about the fact that single-disk-parity VDEVs (hence the comparison RAIDZ1//RAID5) are not recommended to be used with disks larger than 1TB. :D

??? Can you explain me? Maybe about that resilvering a large disk can destroy the source and so lose all the pool?

 

[wblock]

As I recall, the numbers were for a 12TB array, typically three 4TB drives. The 1TB thing is local to these forums, possibly overcautious.

The idea is that, if failure rates are accurate, a failure occurs on one drive. Before the replacement for that drive has finished resilvering, another error occurs on another drive. Data is lost or the array fails.