question about raidz2 storage

[redking]

I am finally ready to move all my data over to my Freenas setup, and with that I have started to experiment abit with some virtual drives before I wipe my drives for the move to ZFS to make sure I am upp and running again as soon as possible.

I tried making a pool with the volume manager. I added 6 drives with 3GiB and choose raidz2. Inside the volume manager it says this is going to give me a capacity of 4GiB, and when I press the add volume button, I end upp with a storage volume with 6GiB available, and a dropdown item under with 4GiB available.

So my question here is kinda, what does this mean? do I have a total storage size of 6GiB with 4GiB delegated to some autocreated itemset? I seem to only be able to use the 4GiB storage to create datasets, so kinda feels like the total storage is 4GiB

Also when I use a raid calkulator and put in 6disks with 3GB and choose raidz2, I get 12GB of total usable storage capacity. is this not correct?

the reason I ask is I am trying to figure out how many drives I am going to need. I have 6x 3TB drives available, and I need a minimum of 10TB storage. and I want the security of 2 drives

 

[Mirfster]

Yeah something is not configured correctly. With 6 x 3TB in RaidZ2 you should get roughly 11.5 TB of usable space (ballpark estimate).

Can you post the output of zpool status and zpool list (in CODE tags)?

 

[redking]

Yeah something is not configured correctly. With 6 x 3TB in RaidZ2 you should get roughly 11.5 TB of usable space (ballpark estimate).

Can you post the output of zpool status and zpool list (in CODE tags)?

Thanks for the reply! really appreciate the help

zpool status:

Code:

[root@freenas ~]# zpool status                                                                                                     
  pool: freenas-boot                                                                                                               
state: ONLINE                                                                                                                     
  scan: none requested                                                                                                             
config:                                                                                                                             
                                                                                                                                   
        NAME                                          STATE     READ WRITE CKSUM                                                   
        freenas-boot                                  ONLINE       0     0     0                                                   
          gptid/9200abc5-51f1-11e6-aea8-90e2ba39d229  ONLINE       0     0     0                                                   
                                                                                                                                   
errors: No known data errors                                                                                                       
                                                                                                                                   
  pool: test                                                                                                                       
state: ONLINE                                                                                                                     
  scan: none requested                                                                                                             
config:                                                                                                                             
                                                                                                                                   
        NAME                                            STATE     READ WRITE CKSUM                                                 
        test                                            ONLINE       0     0     0                                                 
          raidz2-0                                      ONLINE       0     0     0                                                 
            gptid/9b3ba988-65a1-11e6-91ae-90e2ba39d229  ONLINE       0     0     0                                                 
            gptid/9b760363-65a1-11e6-91ae-90e2ba39d229  ONLINE       0     0     0                                                 
            gptid/9ba4f09c-65a1-11e6-91ae-90e2ba39d229  ONLINE       0     0     0                                                 
            gptid/9bcfefd2-65a1-11e6-91ae-90e2ba39d229  ONLINE       0     0     0                                                 
            gptid/9bfd2cc4-65a1-11e6-91ae-90e2ba39d229  ONLINE       0     0     0                                                 
            gptid/9c2a2f5a-65a1-11e6-91ae-90e2ba39d229  ONLINE       0     0     0                                                 
        spares                                                                                                                     
          gptid/9c5b6307-65a1-11e6-91ae-90e2ba39d229    AVAIL                                                                       
                                                                                                                                   
errors: No known data errors  

zpool list:

Code:

[root@freenas ~]# zpool list                                                                                                       
NAME           SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT                                                   
freenas-boot  99.5G   609M  98.9G         -      -     0%  1.00x  ONLINE  -                                                         
test          5.97G   363K  5.97G         -     0%     0%  1.00x  ONLINE  /mnt 

 

[Mirfster]

What are your system specs? If these are truly 3TB drives, then something is not seeing the drives for their full capacity...

Can you post output of camcontrol devlist as well?

 

[gpsguy]

Are you sure that all of the disks are 3TB?

Please provide detailed information regarding your hardware. Some older hardware might only allow you to use 2.2TB of a 3TB+ hard disk.

 

[Robert Trevellyan]

virtual drives

6disks with 3GB

By default FreeNAS reserves 2GB of each disk for swap.

 

[gpsguy]

Good catch, I'm sure Mirfster and I both read 3TB, instead of 3GB.

By default FreeNAS reserves 2GB of each disk for swap.

 

[redking]

By default FreeNAS reserves 2GB of each disk for swap.

ye, that kinda explains why this experiment failed :) tried with some virtual 300gb drives, and things looked more like expected suddenly.

Thanks for the help!

 

[SweetAndLow]

You seen really concerned about total storage so I'll point out that you should only fill your pool to about 80% full and you should not go over 90% full. So if you need a min of 10TB you should probably get 6x4TB drives in z2. This will give you 11.5TiB of space that you can actually use.

 

[Mirfster]

By default FreeNAS reserves 2GB of each disk for swap.

Good catch, I'm sure Mirfster and I both read 3TB, instead of 3GB.

+1 Wow, totally missed that. Good Catch.

 

[redking]

You seen really concerned about total storage so I'll point out that you should only fill your pool to about 80% full and you should not go over 90% full. So if you need a min of 10TB you should probably get 6x4TB drives in z2. This will give you 11.5TiB of space that you can actually use.

Thanks for pointing this out! going over to 4TB drives might not be the best idea here as I allready have the 6 3TB drives ready. But getting 1 or 2 more 3TBs shouldnt be a problem.

also I am wondering how much ram I should run my freeNAS with, if I have, lets say 8 3TB drives? will 20GB be enough?

edit: I have up to 32GB ddr4 ram availeble for FreeNAS.

 

[Robert Trevellyan]

will 20GB be enough?

Almost certainly.

I have up to 32GB ddr4 ram availeble for FreeNAS.

If you have it, use it.