Register for the iXsystems Community to get an ad-free experience and exclusive discounts in our eBay Store.

Slideshow explaining VDev, zpool, ZIL and L2ARC for noobs!

Wolf666

Junior Member
Joined
Mar 20, 2015
Messages
14
Thanks for the guide, together with official documentation and forum is a good start for design your FreeNAS gear.
 

pnolans

Newbie
Joined
Mar 30, 2015
Messages
3
I would like to add my thanks as well. You answered a LOT of questions for me.

Thank you very much for this effort.
 

clugo633

Junior Member
Joined
Apr 16, 2015
Messages
18
Thanks for the guide. Very helpful. I'll still need to read a few more time...but at least theres something out there. :)
 

Neil_Solaris

Newbie
Joined
May 5, 2015
Messages
3
There are several slides (#14, 17, 36) in the presentation that refer to "ZFS version". This is incorrect, those are the "Zpool version".
Both the ZFS and the Zpool have a version number. They are not the same, and are not interchangeable.
Most systems are ZFS version 5.
To see both numbers on your own system, you can run the following commands:

# zfs upgrade -v
# zpool upgrade -v

Note, if the above commands are run with "-a" option, they actually perform an upgrade. This cannot be undone! There is no back-out if you change your mind! But without the "-a" they don't change the system and are safe to run.
 
Last edited:

Neil_Solaris

Newbie
Joined
May 5, 2015
Messages
3
Slide #9 says,"ZFS can detect and correct for “silent corruption” by using parity data and mirrors."
Actually, the parity data and mirrors are only used for the correction part. The detection part of "silent corruption" is done by the end-to-end checksums. This detection of silent corruption feature exists even on a single disk VDev with no parity data and no mirror.
 

draggy88

Neophyte
Joined
Jun 19, 2015
Messages
9
Im a newb user of both ZFS and Freenas so excuse my ignorance! What does confuse me is the Freenas UI vs. ZFS acronyms.
ZFS: Harddrive, Vdev, Zpools
Freenas: Disks, Volume, Datasets and Zvol.

Could anyone care to explain the connection between these 2 acronym sets?

Is a zfs Vdev the same as a freenas Volume ? What is a zvol then?
Is a dataset the same as a Zpool?

br Thor
 

adrianwi

Neophyte Sage
Joined
Oct 15, 2013
Messages
1,145
My understanding would be:

Harddrive=Disks
Zpool (which can made made up of one or more Vdevs)=Volume

One or more Datasets can be created within a Volume and not sure about zvol :D
 

Ericloewe

Not-very-passive-but-aggressive
Moderator
Joined
Feb 15, 2014
Messages
16,830
Zvols and datasets are ZFS structures that exist in ZFS pools. Each works like an independent filesystem.

Volumes are pools (a bit confusing, but hopefully improved in FreeNAS 10).

Pools are made up of one or more vdevs.
 

draggy88

Neophyte
Joined
Jun 19, 2015
Messages
9
thx for the response, but is there a way to display the vdevs in the freenas ui ? I see only volumes (zpool) and disks.
 

Bidule0hm

Server Electronics Sorcerer
Joined
Aug 5, 2013
Messages
3,710
Select the volume you want to see the vdevs (the top-level one, not a dataset) and click on the button "Volume Status" ;)
 

draggy88

Neophyte
Joined
Jun 19, 2015
Messages
9
thx for the expl!! tho im still confused ;) Ive a volume is the same as a zvol, and datasets are made under the volume, how come one can make a zvol again under a dataset?
 

Bidule0hm

Server Electronics Sorcerer
Joined
Aug 5, 2013
Messages
3,710
"volume" in the GUI is equivalent to "pool", not zvol. Zvols and datasets are two ways of using a pool, a bit like you make directories to sort your data (and you can make recursive directories, same here) ;)
 

Rainwulf

Member
Joined
Jul 12, 2015
Messages
67
This is a fantastic read through, and im glad i read it now before i started to do serious work with FreeNAS.
I am on the bleeding edge as well due to having the 8tb seagates, so this has been very useful.
 
Joined
Sep 13, 2014
Messages
141
This is just a note of thanks, skip ahead.

I'm ashamed to say that I've only just got around to reading through the guide in preparation for my first server. Thanks for the time and effort you put into it Cyberjock.

I'm happy to say that I knew about half of what was in the guide thanks to the research I've done up to this point (and all the informative conversations I've read on this forum) but there's some stuff that's new to me and very helpful to know. I think I've done everything right so far and (aside from one or two non-critical choices) the guide has reassured me that I'm right to be happy with the hardware I've chosen... I just wish I could get rid of the nagging "RAIDz2 isn't enough" voice in the back of my head!
 
Joined
Sep 11, 2014
Messages
193
This is just a note of thanks, skip ahead.

I'm ashamed to say that I've only just got around to reading through the guide in preparation for my first server. Thanks for the time and effort you put into it Cyberjock.

I'm happy to say that I knew about half of what was in the guide thanks to the research I've done up to this point (and all the informative conversations I've read on this forum) but there's some stuff that's new to me and very helpful to know. I think I've done everything right so far and (aside from one or two non-critical choices) the guide has reassured me that I'm right to be happy with the hardware I've chosen... I just wish I could get rid of the nagging "RAIDz2 isn't enough" voice in the back of my head!
RAIDz2 should be plenty. Just remember it is a redundancy, not a backup.
 
Joined
Sep 13, 2014
Messages
141
RAIDz2 should be plenty. Just remember it is a redundancy, not a backup.
Thanks for the friendly reminder but I definitely haven't forgotten that RAID isn't a backup.

The reason why I have the "RAIDz2 isn't enough" voice in my head is that I'm not happy with my current backup solution. I shames me to admit it be my current storage server isn't backed up. I have the important data on it duplicated manually across two or three WD Red's and most of said data on a laptop but knowing full well that I have very little protection is what prompted me to go with FreeNAS, or more specifically, ZFS. My FreeNAS sever will be backed up using Crashplan and I'll keep a copy of the truly precious data on my old WD Red's but that's only an imperfect stopgap measure until I can get a decent local (or nearby i.e. at my relatives house) backup of my data on another ZFS system. I can only do what my budget allows though.
 

lmannyr

Member
Joined
Oct 11, 2015
Messages
164
Google doc PDF under "long term server maintenance" the google hard drive link is dead.
 

Mirfster

Doesn't know what he's talking about
Joined
Oct 2, 2015
Messages
3,214

rbid

Neophyte
Joined
Nov 16, 2015
Messages
10
Excellent one, thanks.

Question: If I have a poor FreeNAS hardware that meets the minimum requirements (8GB RAM), will this work without critical problems when it is loaded with ~6TB of data (RAIDZ or RAIDZ2)?

In your slides you mention that it is advised to have 1GB per every TB as additional RAM.

Thanks in advance.

--- Ricky Marek.
 
Top