Online Capacity Expansion

[DATAstrm]

I am interested in building a raid 5 array, but I have a question about OCE. I've read that you can use OCE to expand from say 3 drives to 4 drives. I am wondering if you can use OCE or something else to expand from say 3x250gb to 3x500gb by swapping out one drive at a time, and having it recognize the entire 1tb of space after you swap in the last 500gb drive?

The reason I ask is because I'd like to get a controller card that will last a while. Drives now are pretty cheap, 100 dollars for say a 500gb drive. Controller cards are pretty expensive if you want a good one. Say 2 years down the road when 1TB drives are 100 dollars, will I have to rebuild my array or will I be able to simply swap those in 1 at a time to double my space?

Also, I am thinking of getting a 4 port controller to start. I've seen some controllers that can link with other controllers, ie 2x4 ports can link to form 1x8port and form 1 array. What is this called? (ie what do i look for when i'm searching for a controller?)

Thanks in advance!

DATAstrm

 

[eth00]

Online expansion does not work like that, it lets you expand the current array with the same size disks. If you want to create a new size array you need to start fresh.

I am not sure on what they call the ability to link the cards, I am not sure if there is an official name for it.

 

[Cyrilix]

Datastrm, yes, you can have it work that way. For example, OCE in the Thecus N5200 unit works like that. Swap them out one at a time and at the end, you will have all the space. Note, however, that this will probably take you a really long time.

 

[eth00]

Datastrm, yes, you can have it work that way. For example, OCE in the Thecus N5200 unit works like that. Swap them out one at a time and at the end, you will have all the space. Note, however, that this will probably take you a really long time.

Interesting, I did not know that! Ill have to take a look into that feature to see what cards support it.

 

[unhappy_mage]

I am wondering if you can use OCE or something else to expand from say 3x250gb to 3x500gb by swapping out one drive at a time, and having it recognize the entire 1tb of space after you swap in the last 500gb drive?

Generally speaking, this works, but the partition won't grow automatically, nor the filesystem. If you're hoping this will yield one big drive, you'll need additional steps. If you're okay with multiple drive letters on one big array, you're (probably) all set.

 

[DATAstrm]

Thanks for all the replies!!

So generally, to grow a raid system, the only reliable method is to add more disks (and more controllers)? I was mainly hoping to double/quadruple the volume every few years with this method without rebuilding the array--but if the filesystem doesn't grow, then its pointless.

I've been looking at Free NAS as a cheaper alternative to buying a raid controllre then suddenly found out that it doens't support any form of OCE! So what's the point of implementing RAID5 with FreeNAS if you can't grow your volume (with the addition of more drives)?

Anyone know of any free/cheat solution to this? I'm basically looking for an alterative to buying expensive raid controllers in building a Raid5 box with room to grow.

DATAstrm

 

[Sparkyy]

If you add a new drive to the system, regardless if it is the same size or if you are trying to replace 500's with 1 tb drives, what you need to do is first allow the controller to migrate to the new drive. Once that is done and the system is ready, expand to the new partition.
This way, if you just added a new 500 or doubled your size of drives, you will be able to use all that newly formatted space, however if you didn't set your partition to GPT, then you can only go up to 2 TB before having to create a new drive letter to use the left over space.