Disk Defragemntation and LZS

[Craig Kawahara]

Just asking for some clarification regarding the disk drive terminology. FreeNas 10.1 says the NAS drives (2, 2 TB) in LZ1. Is LZ1 and LZS one in the same, just the '1' is denoting a RAID1 configuration? Also is LZS self defragging?

 

[dlavigne]

???

Note that 10.x is still in pre-alpha stage so it's quite possible that it's not even returning real information...

 

[Ericloewe]

???

+1

I have literally no idea what is going on, OP. Your terminology makes no sense, where did you get it from?

 

[depasseg]

I have literally no idea what is going on, OP. Your terminology makes no sense, where did you get it from?

Thank god it's not just me.

 

[jgreco]

Nothing in ZFS is "self defragging".

 

[danb35]

Your terminology makes no sense, where did you get it from?

...and, with apologies if this is piling on, but what OS are you actually running? There's no such thing as FreeNAS 10.1 that I can find, even in development (there's 10.2 and 10.3, but no 10.1). Other than that, I'm afraid I'm as confused as everyone else. I can only assume that you mean ZFS when you say LZS, but even making that mental substitution doesn't make things any clearer for me.

 

[Craig Kawahara]

My apologies to the readers of this post. In an attempt to get a handle on Windows terms versus FreeNas (linux) terms I just made a mess of things. I have always been just a Windows user and this is my first venture into anything other than that. I hope the following is better.

My just installed FreeNas is:
FreeNas version 9.10 running on a 250gB drive on ADA0.
ADA1 and ADA2 are each a 2 TB drive which are in LZ4 compression. I presume it's a mirrored RAID setup (the other option I could have used was 'striping' which I guess is equates to RAID 0 in a Windows device). It has no directory services and allows guest access. The drives are not hardware raid drives.
The sharing of /mnt/FreeNas01/FreeNas01 using Windows (CIFS) with one Windows 7 workstation. The purpose at this point in time is just a repository of files. All malware checking, and antivirus checking is being done on the workstation. The FreeNas server is only on during the backup period.

Searching the internet, I find several posts (some old) about philosophies dealing with defragmentation. Some pro, some con. The last post I saw dealt with freeNas having no support for defragmentation.

Question: Is the lack of defragmentation for a FreeNas file server an indication that defragmentation is not needed/desired?

Regarding the ZFS file format, did come across this article (http://www.freenas.org/blog/freenas-worst-practices/) which did equate ZFS Striping to Raid 0 and ZFS Mirroring to Raid 1. The article also says the FreeNas used the ZFS format and since the GUI says the drives are in LZ4 compression, it tells me LZ4 is some variant of ZFS. I note that the system specs for Ericloewe says RaidZ2 and for depasseg it says RaidZ-1. I cannot locate anything other than LZ4 on my device.

Question: Am I correct here? ZFS Mirroring = LZ4 = RAID-1?

 

[ttabbal]

You should probably read up on ZFS and RAID in general.... But here's a short version...

RAID0 = Stripping (Zero redundancy, one disk dies, all data is lost)
RAID1 = Mirror (Every disk has a copy of every other disk's data)

raidZ1/raidZ2 = ZFS RAID (sort-of)... You need 3 disks minimum for a raidZ1, one disk worth of data is parity data. So you can lose one disk and the other two will have all your data. Z2 is the same idea, but with another parity disk, meaning you can lose 2 disks and lose no data.

LZ4 is a compression format. It makes the data stored on the disk smaller than the data you wrote to it, if the data can be compressed. It's decompressed on the fly. It has no relation to RAID or raidZ.

ZFS does not require defragmentation and there isn't a tool to do it anyway as it's not needed. This applies for any Operating System running ZFS, not just FreeBSD/FreeNAS.

If you don't know your pool layout, you really should find out and decide if it's what you want. From a command prompt, do "zpool status". From the web UI, you should screenshot or copy/paste the storage screen.

 

[Ericloewe]

ZFS does not require defragmentation

Well, it would certainly benefit from defragmentation, but it's currently impossible to accomplish directly.

 

[jgreco]

Heh, I was going to write a response like that.

 

[JDCynical]

...In an attempt to get a handle on Windows terms versus FreeNas (linux) terms...

In addition to what others have posted, FreeNAS is based on FreeBSD, not Linux.

While the two are similar in many ways, they are also very different on the back end as to how they work. I bring this up becasue if you go looking for information on how to do $THING and it (especially) involves CLI work (which is generally only done in very specific cases and situations as 99% of what one would do with FreeNAS is done via the HTML GUI), information you might find for Linux may not apply or work for FreeNAS.