Media Server RAID question

[hawler]

Hi everyone,

I don't have much experience with servers or RAID (just the RAID 0 in my normal rig) and had a few question. I want to make a media server for all my files. One of the things I've been hoping to implement but can't really find information on is a RAID array that "grows" as i add/replace drives. Is it possible to have a RAID (hopefully 5 or 6) array grow in size as I remove say a 1TB drive and replace it with a 2TB, or take all 1TB drives and swap them for 2TB drives, without losing my data. I've had my eye on a drobo unit which does just his but it is just a storage solution, i would still need a server to hook this up to and the drobo has the problem of if the drobo unit itself dies you lose all the data stored in it. Is it possble to get this "hot swap" functionality in a RAID array? If not i think I'll get a drobo and maybe after a year or two, when i think the chances of it dying are higher, get another one to backup all the data.

I imagine this would require some sort of special RAID card, does anyone know if such a card exists and if so would it have the same weakness (if the card dies the data on the drives is lost)

Thanks in advance

 

[Neogrizz]

As far as I know the thing you want is only possible with Netgear X-RAID2.

See here for X-RAID2 in action: http://www.readynas.com/?cat=53

For example you can't swap all 1TB drives for replacement with 2TB drives at once. You will then lose the protection. But you can swap disks with larger ones, without reformatting the other drives. The system will automatically rebuild the data to the larger disks. Normally a RAID set only works with disks of the same size or will only use the same smaller size of the larger disk, in this case everything is used.

X-RAID2 is patented and I don't think you will see it soon in other solutions from other brands.

 

[hawler]

Thanks, do you know if this suffers from the same problem as Drobo, being that if the device itself crashes the data on the hard drives is lost because they are using a proprietary tech. with drobo if you tried to insert them into a new drobo unit they would get erased as drobo always formats new drives....do you know if this would work the same way or could i disconnect my brives from a busted unit and hook them up to another one and still have it work...i realize these are pretty small details but they are important ones for me.

Thanks again

 

[Neogrizz]

I don't own an X-RAID device myself and can't tell if a failure of the device means total loss of data. Normally a replacement of the same controller, motherboard or device that controls the disks can read the RAID-level from the disks and if the disks haven't failed the RAID-set will work after a block-by-block checkup. I have had a few motherboards with on-board controllers. I didn't have a problem with migrating a RAID-0 set from one to the other, because both had the same Intel controller.

If you want to know for sure you will need to ask Netgear support directly.

 

[goobaah]

I have not tried this, but I believe that you can do what you are saying with the latest Intel chipset. However, you cannot gradually replace the drives and expect to have storage increase. You can replace each drive one by one until all the drives are the larger size. After they are all replaced you can expand the volume to use 100% of the larger drive size. These chipsets also allow you to add more drives to existing raid 5 arrays or conver mirrors to raid 5 or raid 10 arrays, etc. The X58 and P55 MCH chipset and the ICH10DO and ICH10R southbridges can do these things with up to 6 drives.