RaidZ and 4x2Tb yeilds 5.3Tb available space - is this right?

[fortyhands]

Howdy! I hope this hasn't been answered already as I have scoured the net and searched the forum for an answer and nothing turned up.

I just built up a little server box for media streaming:

HP Proliant w/ Athlon Neo 1.3Ghz
8 Gb of ECC ram
8Gb Patriot USB stick
4x2Tb Seagate Green 5900rpm

Things seem to be running all right, but according to come online calculators, I should have 6Tb available, but when I create a raidZ volume in Freenas 8, the web GUI shows as only having 5.3Tb available.

Is this right? Thanks in advance!

Edit: When I navigate to the networked share in OS X, the drive shows 5.87Gb available. Strangeness. Any thoughts?

 

[iustinig]

If you would look on your drives or the package you received them in there should be a note that says 1G=1000000000 bytes. Computers work in powers of 2 - 1G =1024 M 1M = 1024K ... If you take the 1000000000 and divide by 1024's you'll get less than 1G and that is what you are seeing.

You are not being robbed... all the drive manufacturers do this.

 

[fortyhands]

Hey, thanks for the quick response. That would explain the 5.87Tb number I get when accessing the shared volume via os x, but any thoughts on why the WebGUI shows 5.3Tb?

 

[iustinig]

Assuming you have no data then I agree that he 3 numbers should have been closer. I notice now that I'm in the same situation where I cannot account for 2-300G. I looked a bit into it and i cannot figure it out right now. If I'll find anything later I'll post it.

 

[moorrode]

I've had a similar experience. I'm configuring a new FreeNAS 8 box with 5 2TB drives. I initially installed v8.0 and configured a raidz1 volume. The webgui reported a volume size of 7.8TB. I subsequently learned that the v8.0.1 betas added support for 4k sectors, so I installed Beta4, destroyed the old volume, and created a new volume with 4k sectors. My new volume is reported as being 7.1TB

 

[ProtoSD]

I have 5 2TB drives as raidz2 and this is exactly what I have. Somewhere, not on this forum, I saw an explanation of why the 3 numbers were different and it made sense at the time. zpool status, df, and 'whatever' OS all calculate it different. I just picked the smaller one and went with that.

 

[iustinig]

It is not a FreeNAS thing. My storage server would report a corrupted data once a week so i gave up on FreeNAS and moved to ubuntu server with zfs-fuse. The space reported is the same as it was in FreeNAS.

I would keep an eye on those 2T drives. From what i understand they are not that reliable. At my work place we have a 6x2TB raid5 server and we change a drive ~ every 3 months. I would definitely keep a spare close somewhere in a drawer.

 

[metroplex009]

Hey guys,

I came across this thread while searching for ans for something completely unrelated. Just wanted to share some info on OSX reporting different Size. In Snow leopard apple changed the way conversion was done to go from MB -> GB -> TB and vice versa. Hence the number reported on drive size is a little wonky. From what i recall it is suppose to line up with the Marketing gang of Hard Drive manufacturers.

 

[Brand]

In Snow leopard apple changed the way conversion was done to go from MB -> GB -> TB and vice versa.

The conversion between MB, GB, and TB has nothing to do with it. It is a Base 2 vs Base 10 thing.

 

[metroplex009]

Agreed. All I am saying is that apple opted to go with Base 10 from snow leopard onwards hence you will see a difference between what OSX reports and what other OSes report.

 

[jgreco]

It's not just a base2 vs base10 thing. In some cases, filesystems may also hold back a percentage, such as UFS/FFS, which has traditionally held back between 5-10% of the space in order to allow it to perform properly. The moral of the story is that you shouldn't just add up the numbers on the outside of your HDD packages and expect that your computer is going to report anywhere near that number of bytes. Best to expect the actual usable space to be 25% less, then you're likely to be satisfied.

 

[Saeed A Siddiki]

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)

 

[JaimieV]

Saeed, you've posted this about 8 times now, mostly in unrelated threads. Stop it.

 

[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.

 

[Yell]

^ your not better :D

please use the report Button (the tiny /!\ )

 

[cyberjock]

I know. I just didn't want this to be ignored for a second day. I was hoping at least one admin would find at least one of the threads I posted in. Reported though. :)