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Adding drives to a raid 5 to increase storage space


Hello all,

I have a raid 5 array I build for a HTPC/server with aIntel® RAID Controller SRCSASBB8I. Running windows7 64bit.

Never had one issue glad to say except now I am runing out of storage space. I have 6,1TB Drives that yields around 4.8 TB of usable storage.

I thought I could simply connect another drive to the card, scan for it with the web console utility and add it. But the drive doesn't populate,show up in the console.

My questions,

1. It is a new drive I am adding. I didn't format it first. Maybe this needs to be done? It's the same exact drive model as all the others.

2. Is there any risk of corrupting the existing data on the current array when adding additional drives to increase the storage size?

3. In order to be able to do this was I suppose to configure the array a special way when I first initialized the virtual disk?

If it's best to back up all my data deleted the array and start all over because I didn't configure something to be able to add drives like this then so be it. I will do. I just would love to learn what it is that's needed so I don't find myself doing this again.

Thanks in advance for any and all help!!!

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6 Replies
New Contributor I

You should always keep a backup of your data.

When you add the new HD, the RAID controller would know it at bootup. You can add it to the existing RAID at BIOS, or with the Web Console. This is called Online Capacity Expansion or OCE. Look up the controller manual and it should tell you how to do it.

You do not need to format the disk first.

Yes, there is risk of damaging the existing array if you do not do it correctly. So get a backup.

OCE is much easier than rebuilding the entire array. It saves times. If everything goes well, you do not even need to restore from backup. >4 TB data takes a lot of time to copy....

Good luck.


Thanks for helping.

I am having a hard time finding any real instructions on how to perform Online Capacity Expansion.

I have looked in the controllers manual and search Intel's website. I can agree with you this is defiantly what I need to do. I can find explanations about what Online Capacity Expansion is and know my controller card can do it but nowhere can I find detail instructions on how to accomplish it.

Really frustrating as the time I have to dedicate to this project is limited. And I find myself doing nothing but searching endlessly. I have now maxed out my storage and really need to figure this out.

Any suggestions?

I seriously looked at like three PDFs that all pertain to my card and didn't find anything detailed.

New Contributor I

Get some old and small SATA drives you can find. Practice and figure it out. You can first set up a two disk RAID 1. Then try the OCE to set up the RAID 5.

Each RAID controller is different. So I can't give detailed instruction. Nothing is better than first-hand experience....



The expansion can be done using an Intel® RAID Controller SRCSASBB8I; just make sure you keep the RAID level (RAID 5). "Add capacity to the virtual drive. The added capacity can be presented to the operating system as additional space for the operating system to partition it as an additional drive, or it may be added to an operating system drive, depending upon the capability of the operating system." [qtd. on printed page# 32 of the Intel® RAID Software User's Guide].

Important Reminder: "You should always keep a backup of your data." (qtd. by RedSun)

You may want to refer to printed page# 55 of the previously mentioned document for more insight, as an example; notice the described scenario is that of a RAID 1:

Should you wonder, the main, technical site for the RAID controller card in question is found here: Support for the Intel® RAID Controller SRCSASBB8I

Hope that helps!


Great. Thanks!

I can follow these instructions.

I am anxious to give it all a try.

In the process of backing up close to 5TB of data as suggested. This is taking a while.

I am now debating whether I should simply add another hard drive to increase the array or swapped them out for larger capacity drives.

Currently there are six 1TB drives. Adding a seventh 1TB doesn't seem like a much more these days.

Swapping out all 6 drives to 2TB or 3TB drives is a bit more costly but may be best. I see this as an opinion now while as before I didn't and thought I could only add additional drives to the array to increase storage.

Once all is backed up I ll give it all a try.

Thanks again.

New Contributor I

For home use, SATA 3.0 is just fine. But if you have the budget, larger HDs are definitely better since they will be probably SATA 6.0, newer and less wear. Also you save energy and less noisy.....