RAID Question

[Smitty07314]

So, I am beginning the journey to creating a NAS and will be running some sort of RAID (To be determined) My question is say i start with 3 hard drives in a raid format. I now want to add a fourth to increase my total storage. Is it as simple as plugging it in and adding it to the raid. Would any data be lost or will the RAID setup just add it in their with the other hard drives? How do you go about increasing the number of hard drives in a raid. 

[Denned]

Some NAS boxes support custom RAID types allowing expanding a volume. It depends on what box you want to use.

But else you will be recreating the volume in order to add that new drive.

 

[Windows7ge]

That's dependent on how it's configured. Some RAID controllers and some software RAIDs allow for dynamic expansion of the array while others are fixed and cannot be expanded without destroying the existing array and starting fresh. I know FreeNAS (FreeBSD) software RAID allows for expansion of an existing array while preserving the data on it but that's all I can vouch for.

[Enderman]

linus' old home nas system had a raid that you could pull out, replace, or add any drives you wanted

go search for those old videos on the channel

[Smitty07314]

55 minutes ago, Windows7ge said:

That's dependent on how it's configured. Some RAID controllers and some software RAIDs allow for dynamic expansion of the array while others are fixed and cannot be expanded without destroying the existing array and starting fresh. I know FreeNAS (FreeBSD) software RAID allows for expansion of an existing array while preserving the data on it but that's all I can vouch for.

 

46 minutes ago, Enderman said:

linus' old home nas system had a raid that you could pull out, replace, or add any drives you wanted

go search for those old videos on the channel

Thank you both. I just wanted to make sure there was something out there that would allow for me to expand storage without losing data. 

[Sunshine1868]

Like @Denned said, it depends completely upon your RAID solution. The majority of RAID Controller cards will actually delete all data if you attempt to add another drive, while something like FreeNAS (using ZFS) will allow you to dynamically upgrade and change the drives (as long as they are all connected directly to the MoBo or are in a pass-through mode on the RAID Controller)

[trag1c]

From what I understand if you have a decent hardware RAID card then you are able to add drives to an array or replace them with larger capacity drives. I know my Adaptec 5805 supports this(though I have never tried it.). As well as RAID level migration.

[Sunshine1868]

5 hours ago, trag1c said:

From what I understand if you have a decent hardware RAID card then you are able to add drives to an array or replace them with larger capacity drives. I know my Adaptec 5805 supports this(though I have never tried it.). As well as RAID level migration.

One must be careful... with a 3 drive setup (As @Smitty07314 says they are starting with), the only real option to go with is a RAID 5 Setup...Ideally the 3 drives would be the exact same drives. If they are not the same capacity, then the useful capacity would drop to the lowest capacity drive.

Situation 1: Expanding this RAID (still RAID 5, but with an extra drive) MAY be possible, but would probably involve deleting all data from the disks as the RAID controller would want to redo the parity situation.

Situation 2: If you wanted to expand the RAID by 1 drive and change it to RAID 6, it would DEFINITELY require deleting all data as the parity calculations are completely different.

 

Your best bet if you plan to change/upgrade your drives and/or the capacities of the drives do not match is to connect all of the drives in a JBOD (Just a Bunch Of Disks) configuration to the Mo-Bo (or in a passthrough configuration on a RAID controller card) and use an OS such as FreeNAS which utilizes ZFS (ZFS will allow for dynamic array changes and such)

[Smitty07314]

9 hours ago, Sunshine1868 said:

One must be careful... with a 3 drive setup (As @Smitty07314 says they are starting with), the only real option to go with is a RAID 5 Setup...Ideally the 3 drives would be the exact same drives. If they are not the same capacity, then the useful capacity would drop to the lowest capacity drive.

Situation 1: Expanding this RAID (still RAID 5, but with an extra drive) MAY be possible, but would probably involve deleting all data from the disks as the RAID controller would want to redo the parity situation.

Situation 2: If you wanted to expand the RAID by 1 drive and change it to RAID 6, it would DEFINITELY require deleting all data as the parity calculations are completely different.

 

Your best bet if you plan to change/upgrade your drives and/or the capacities of the drives do not match is to connect all of the drives in a JBOD (Just a Bunch Of Disks) configuration to the Mo-Bo (or in a passthrough configuration on a RAID controller card) and use an OS such as FreeNAS which utilizes ZFS (ZFS will allow for dynamic array changes and such)

I have started to do my research on ZFS and was thinking that it would be a safe place to start. Especially if it allows for me to plug and play different drives. So if I went this route it would be important for me to make sure I either get a mobo with plenty of connectors or rely on a raid card but just to increase the number of possible drives correct. THen through the program installed (FreeNAS with ZFS) I would be good to expand and change drives. Meaning no raid setup

[Sunshine1868]

16 minutes ago, Smitty07314 said:

I have started to do my research on ZFS and was thinking that it would be a safe place to start. Especially if it allows for me to plug and play different drives. So if I went this route it would be important for me to make sure I either get a mobo with plenty of connectors or rely on a raid card but just to increase the number of possible drives correct. THen through the program installed (FreeNAS with ZFS) I would be good to expand and change drives. Meaning no raid setup

ZFS does not allow for "plug 'n play"... It simply allows for changing and expanding if you configure it to do so. You need to give any RAID time to rebuild/alter itself when you reconfigure. Be extra careful "telling" ZFS what you are doing with your disks before you destroy all of your data!