Basics of ZFS

[chachi420]

Hello everyone,
I have seen so many videos and read so much about ZFS but all of the information was in a way too detailed to get the basic idea of ZFS. I need to understand ZFS is in a very simple language! This is what I understand about it so far.
It is unique in that it creates snapshots which is sort of like a backup of your data and you can retrieve it if you accidentally deleted it. Another thing I understand is that ZFS is created in pools so like from what I understand a pool is simply just a bag in which you can place multiple HDDs and the system will recognize the BAG itself as one single HDD with the volume equal to the combined volume of the multiple HDDs inside the bag.

Okey now if my understanding of the pool system is correct, then let's say that I want to create a raid 1 storage with only 2 one terabyte HDDs. It would mean I would have to create two pools or should I say two BAGS, and I put one HDD in each bag (yes, to me it doesn't make any sense why I would need to create a pool when there's just one HDD in it. Couldn't the HDD be by itself outside the pool (BAG) in this case? ) and then simply create a raid 1 system. Am I understanding it correctly?

Now let's say that I seriously don't have much data I mean I barely have like about 500GB worth stuff that I DO already back up on an external HDD so I don't really need a sophisticated system ok? And I i just wanted to create a raid 1 system so that the data that I already have on my external hdd is also on both the raid 1 HDDs. So as you can see, I have 3 copies of my files in 3 places. This is a perfect backup system that I can ask for ok? So, if i just want to do that much, should I even go for ZFS? Or will UFS be just fine enough for this purpose? And since I know that I could do raid 1 in zfs too, would there be any benefit to choose zfs over ufs in my case? Speed maybe? I mean the current system I have is alright (CPU: x64-embedded on AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ and about 3GB of RAM and 3 different UFS mounts) and I am getting about 70MB/s read and write speed on all three of the HDDs. The HDDs I have are 7200 RPMs and the highest cache is 16 Mb in one of those three HDDs. So based on this current configuration, would ZFS be of any benefit?

Yes, these are too many questions but I thought I should ask all the questions in a single place so it will be easier to obtain answers rather than having multiple threads for it. Thank you for all your support.

[raulfg3]

more info for you: http://forums.freenas.org/index.php?thr ... oobs.7775/

This powerpoint is really easy to understand.

[b0ssman]

please read this first
http://forums.freenas.org/index.php?thr ... zfs.15449/
and then here is a good slide explainning zfs
http://forums.freenas.org/index.php?thr ... oobs.7775/

basically you create a zfs mirror vdev and add that vdev to one pool.

[chachi420]

Thank you guys. I have seen this powerpoint before but it was still difficult for me to understand. I will try to read it once again and this time maybe at the beach haha. If I still have any particular questions, I will come back and post them here.

[raulfg3]

more advanced info about ZFS and optimun number of disk in a pool:

http://blog.delphix.com/matt/2014/06/06 ... ipe-width/

https://pthree.org/2013/12/10/zfs-admin ... e-ecc-ram/