Plans

[canuck]

Hi
Just installed freenas 8 to test it out I have never built one and have been using external drives to backup but would like a better solution. I have a few questions about the setup. I am prepared to have 3 separate raids if this is best. I plan on using my raid to store music, movies etc. I also need it to back my laptops/machines have 4 on my home network. Currently I have 3 WD black 2TD drives in a ZFS setup. I noticed you can only added larger drives to add space. I do not like this approach.

Can I not in the future buy 3 more 2TD drives and mirror the first volume. This means that 3 drives would need to fail on both arrays at the same time to lose all my data (2 in one array and 1 in the other one). As an added benefit read performance would also increase which would be a bonus. This configuration would support my music/movies. I can then build a third raid with 5 disks in a ZFS setup that would act as a backup device for my computers (means a total of 6 disks) 10TB of data. I am currently using an old dell studio as my NAS server it is slower but read/write performance is not an issue for my network backup but I will buy a faster machine for my music/movie server.

So does this plan make sense. Money is an issue and I think this allows me to grow the system as I get comfortable with it and see that it works.

 

[cyberjock]

I'm a little confused on what you are trying to do. I just woke up so it could be that I'm still a little asleep. Read my guide(link in the sig) and that should help you understand how zpools work and how you can grow them(or not grow them). Then you should be able to identify if what you are wanting to do is possible.

 

[fracai]

Your plan is a little confusing (it seems like you're inconsistent in how many disks are involved), but let me try to rephrase.


To start off: 3 drives, 2 TB each in RAIDZ1 = ~ 4 TB useable. Two drives failing at the same time would result in data loss

Later: add 3 more drives, 2 TB each in RAIDZ1 as a MIRROR of the first set = ~ 4 TB useable. Four drives failing at the same time (two in each mirror), would result in losing all data. Actually, I don't think you can turn a RAIDZ1 into a MIRROR of multiple RAIDZ1s. I'm not sure there'd be any reason to anyway.

Instead: add 3 more drives, 2 TB each in RAIDZ1 = ~ 8 TB useable. Two drives failing in the same RAIDZ1 array would result in losing all data from both arrays.

Preferable, though costly: start with 6 drives in RAIDZ2 = ~ 6 TB useable

Or, instead of adding 3 drives, replace the current 3 with larger capacity. Replacing three 2 TB drives with three 3 TB drives when they're much cheaper would yield 6 TB.

Or, instead of adding the 3 drives to the same pool, create a new pool. You'll have to manage which pool your data goes to, but losing one RAIDZ1 wouldn't mean losing the other.



cyberjock's guide is a good starter.

 

[canuck]

Thanks for the replies. I had already looked over cyberjock's document and spent a lot of time on this site thinking things over as a shadow. Let me try to explain my plans again I may have the number of drive failures wrong. I see my network having 2 separate nas machines. One used as a media server with faster read requirements and a second nas machine that will backup my data (all data including the media machine). This second machine does not need the horsepower of the first machine (can be slower hardware etc).

I would like to reuse some of my existing laptops and other hardware. My understanding was that using fewer HD would result in faster reads so that is why the 3 HD setup for my media machine. While a larger disk array will result in better fail safes. Am I missing something?

 

[fracai]

That sounds reasonable, though if you're going for read speed you should use mirrors. And your reference of reusing existing laptops makes it sound like you might be connecting drives by USB. That's not a good idea and can increase the risk of data loss.

 

[canuck]

Well currently my three drives are in an external mediasonic 4 bay box. plan is to put these in my media machine once I buy it. If I want a mirror does that mean a total of 5 drives? or how many mirrors should you use? and you cannot create a mirror after the fact without destroying your data?

So how do people build these 9 disk arrays I do not think you can buy that size chassis except as an external connection.

 

[fracai]

A mirror can be two drives or three drives; I'm not sure if you can have a mirror higher than that, but I wouldn't be surprised. You can have multiple mirror arrays in a pool, so the design is up to you. I was just mentioning that a mirror is going to give you the best performance.

Do a search for "9 bay tower". There are plenty of options and 9 certainly isn't the limit on the number of bays that a chassis can hold. Rack chassis' can easily hold more.

 

[Caesar]

Well currently my three drives are in an external mediasonic 4 bay box. plan is to put these in my media machine once I buy it. If I want a mirror does that mean a total of 5 drives? or how many mirrors should you use? and you cannot create a mirror after the fact without destroying your data?

So how do people build these 9 disk arrays I do not think you can buy that size chassis except as an external connection.

What you do is get a case with 9 5.25 bays and then you get 3 of these. http://www.newegg.com/Product/Product.aspx?Item=N82E16817994077 this will give you 15 drives in a standard Full Tower case.

 

[canuck]

thanks. so if I understand the more mirrors the faster the read but the mirrors need to be defined (created at the start of the build). But the idea of separate nas machines for different purposes does not appear unusual.

this is what I currently am using

http://www.newegg.com/Product/Product.aspx?Item=N82E16817576009

just one less bay.

 

[fracai]

Sorry if that was confusing, but you can actually add drives to a mirror. In other words, you can add a drive to a two drive mirror to turn it into a three drive mirror. I just don't think you can turn a RAIDZ array into a MIRROR of RAIDZ arrays.

 

[cyberjock]

fracai has it correct. You cannot convert a vdev into a different vdev with one exception. You can add another mirror drive to a vdev that is single disk or a mirror already. Alot of people kept screwing this up and getting upset which is why I included this in my guide(link in my sig if you haven't read it already).