FreeNAS 8 raidz incorrect size?

[snowmirage]

I've been using FreeNAS for sometime now and am looking to build a new system.

I was looking to setup raidz across multiple drives before buying new hardware I wanted to check it out in a VM on my esxi box.

I setup FreeNAS-8.0.1-RC2-amd64 with 3GB of ram and creates 5x5GB virtual disks to add to the VM

From what I have read the size calculations for raidz should be Number of disks - 1 * size of the smallest disk

so in my case it should be (roughly)

5 disk - 1 disk * 5GB = ~20GB of useable storage

I even saw an example of someone building a similar box using 5 750GB drives he ended up with ~3TB of useable space, which is great

however when I create the raidz with my 5 x 5GB drives I end up with it telling me I have "11.7GB" available.

I'm not sure whats going on here.

even if it was defaulting to raidz2 (which should be N drives - 2 * size ) i should still have 15GB of space.

If anyone could point me in the right direction here I would greatly appreciate it, I've been searching around for a while but I'm not coming up with much.

 

[danb35]

The system is using 2GB (on each disk, I think) as swap, so you really have 3 GB x (5 disks - 1 disk) = 12 GB.

 

[Durkatlon]

You can avoid this swap business if you set up the array from the command line instead of the UI, but you cannot set the swap to be 0 from the UI itself. In a non-toy setup where the disks will be much larger, you will not really notice the swap space, since as a percentage of total drive size it will be negligible.

I got stung by this in my VMWare instances when I had initially built a 2x4GB mirror in the command line for a total of 8GB space. Then later I built a 4x4GB striped mirror in the GUI and again got an 8GB array out of it. Whoops

 

[snowmirage]

So this swap reservation is part of the ZFS system then or something specific to FreeNAS? And is there anyway to see how this is allocated, some way I could have found this myself, just for the sake of building a better understanding. Thanks for the response, that makes sense now anyway.

 

[Durkatlon]

It's configurable from System>Settings>General. Now, it says the following: "Swap size on each drive in GiB, affects new disks only. Setting this to 0 disables swap creation completely (STRONGLY DISCOURAGED)." This is in 8.0.1-RC2 and it implies that you can in fact set it to 0 and it will use the entire disk for storage.

In 8.0.1-BETA4 (System>Settings>Advanced) it used to say "Swap size on each drive in GiB, affects new disks only. Must be non-zero", so running without swap was not supported.

 

[snowmirage]

Ok thank you

and lastly is this FreeNAS overhead or something I am just unfamiliar with in ZFS?

 

[snowmirage]

And for others information in the version I am using FreeNAS-8.0.1-RC2-amd64

it is found under

System > Settings > Advanced

and reads

"Swap size on each drive in GiB, affects new disks only. Setting this to 0 disables swap creation completely (STRONGLY DISCOURAGED)."

 

[Durkatlon]

Sorry, yeah it is under Advanced, not General. Not sure why I got that wrong. Anyways, the swap is part of FreeBSD, it has nothing to do with ZFS. If you go into the shell and type "pstat -s", you can see the swap partitions being used. You can also see them on the disks using "gpart show". Here's what both commands do on my box:

Code:

[root@buckyball] /tmp# gpart show
=>     63  7716744  da0  MBR  (3.7G)
       63  1930257    1  freebsd  (943M)
  1930320       63       - free -  (32K)
  1930383  1930257    2  freebsd  [active]  (943M)
  3860640     3024    3  freebsd  (1.5M)
  3863664    41328    4  freebsd  (20M)
  3904992  3811815       - free -  (1.8G)

=>      0  1930257  da0s1  BSD  (943M)
        0       16         - free -  (8.0K)
       16  1930241      1  !0  (943M)

=>      0  1930257  da0s2  BSD  (943M)
        0       16         - free -  (8.0K)
       16  1930241      1  !0  (943M)

=>        34  2930277101  ada0  GPT  (1.4T)
          34          94        - free -  (47K)
         128     4194304     1  freebsd-swap  (2.0G)
     4194432  2926082703     2  freebsd-zfs  (1.4T)

=>        34  2930277101  ada1  GPT  (1.4T)
          34          94        - free -  (47K)
         128     4194304     1  freebsd-swap  (2.0G)
     4194432  2926082703     2  freebsd-zfs  (1.4T)

[root@buckyball] /tmp# pstat -s
Device          1K-blocks     Used    Avail Capacity
/dev/ada0p1       2097152        0  2097152     0%
/dev/ada1p1       2097152        0  2097152     0%
Total             4194304        0  4194304     0%
[root@buckyball] /tmp#

 

[snowmirage]

Ah ok its FreeBSD overhead, I completely get a swap Partition for the OS or something but dont see any reason to reserve 2GB on every drive you add.

Must be something in FreeBSD I dont understand since I'm unfamiliar with it.

 

[Saeed A Siddiki]

guys really am rattling my head around this issue of actual SPACE reported by the GUI! WOULD APPRECIATE ANY HELP ON THIS


my situation:
The hard drives are the regular run of the mill in these capacities - green drives and one WD Blue Drive:

4 X 1TB * = *4
3X 2TB*= *6
2X 3TB *= *6
1X * 750GB = *750 GB *

TOTAL TO = 16TB physical*
-3tb overhead (in theory)

i should end up at least with at least 12 TB OR 10TB ---

BUT WHATS SHOWING under

RAIDZ IS 5.6TB*and

under RAIDZ2 5.3TB
(i still don't have REAL DATA stored on this volume yet)

The Calculator link is suggesting: (which is all jibrish FOR ME at this point)
guys i have a bigger gap in my array and i am a newbeee and am sure i am missing something here! please help ...

The hard drives are the regular run of the mill in these capacities - green drives and one WD Blue Drive:

4 X 1TB * = *4
3X 2TB*= *6
2X 3TB *= *6
1X * 750GB = *750 GB *

TOTAL TO = 16TB physical*
-3tb overhead (in theory)

i should end up at least with at least 12 TB OR 10TB ---

BUT WHATS SHOWING under
RAIDZ IS 5.6TB*and
under RAIDZ2 5.3TB (i still don't have REAL DATA stored on this volume yet)

 

[cyberjock]

Saeed A Siddiki has 7 posts today, and 6 from yesterday, all asking the same question. Please, forum moderators, do something. This is just out of control. I thought I made it clear yesterday when I posted to all of his threads to stop, but he's back today.

He needs to be banned, prevented from posting, or something, until he understands that posting to multiple threads won't give you more answers. Not to mention that his question doesn't have much to do with the threads he's posting in.