[Help] RAID 6 expansion

[zeroibis]

I have a 2TB drive that is getting full and so I have invested in a RAID 6 setup to add more space and solve my long term storage issues.

I have built a 4TB array using 4 drives(2tb each, so 4tb usable after n-2) so that I can copy the data from the 2TB drive over before formatting it and then adding it to the raid 6 for a total of 6TB then later when my drive comes back from rma I will be adding another 2tb for a total of 8tb.

I am using a hardware raid controller from areca and it offers a function called expand raid set. Apparently I can pop in the extra drive and increase the size of the array without losing data. However before I end up losing all my data I got a few questions:

(Running win 7 ultimate)

1) Is it as simple as expanding my raid set (my controller has a function for this) and then just using Disk Management to extend the volume to include the unallocated space?

2) If I expand my raid set using the raid controller will I get the extra usable space in windows in that I will end up with a 6tb partition instead of 4tb?

3) If the answer to 2 is NO then what do I need to do in order to expand the partition from 4 to 6tb without losing my data?

Thank you for the help

[DTR]

I have a 2TB drive that is getting full and so I have invested in a RAID 6 setup to add more space and solve my long term storage issues.

I have built a 4TB array using 4 drives so that I can copy the data from the 2TB drive over before formatting it and then adding it to the raid 6 for a total of 6TB then later when my drive comes back from rma I will be adding another 2tb for a total of 8tb.

I am using a hardware raid controller from areca and it offers a function called expand raid set. Apparently I can pop in the extra drive and increase the size of the array without losing data. However before I end up losing all my data I got a few questions:

(Running win 7 ultimate)

1) Is it as simple as expanding my raid set (my controller has a function for this) and then just using Disk Management to extend the volume to include the unallocated space?

2) If I expand my raid set using the raid controller will I get the extra usable space in windows in that I will end up with a 6tb partition instead of 4tb?

3) If the answer to 2 is NO then what do I need to do in order to expand the partition from 4 to 6tb without losing my data?

Thank you for the help

First off, this is general info - not specific to your configuration but helpful non-the-less.

Second, you will NOT get 4 TB of space using 4 drives (assuming 1TB drives) Max usable space with Raid 6 is N-2 (where N is the number of drives) Soooo you will only have 2TB of space (but dual redunancy - two drives can fail). If you used Raid 5 (single drive redundancy) you will have N-1 or 3 TB of storage.

Even more terrible is that a 1TB drive is only 930GB after formating so 4 drives only gives 3.7TB raw space - 930GB (N-1)for redundancy and you have 2.7 TB of actual storage in raid 5 or 1.8TB in raid 6.

Now answering your questions:

1) I can't speak for your specific controller but the Intel ICH10R on most motherboards will do exactly what you want. So you have to look into that specifically, the ICH9R will not for example.

2)Generally speaking, you can NOT mix drive sizes*...in your example you started with 4 1TB drives, so you can't add a 2TB drive (see note below)

3) If your controller is like the ICH10R (already included in virtually all new boards) simple continue to add 1TB drives till the hit the max drive count for your controller (6 drivers for the ICH10R).

Note:
To expand the total space of a full array, so lets say 6 1TB drives in Raid 5 for 4.6TB of storage (remember N-1) you can start replacing the 1TB drives with 2TB (or if available 3TB) drives. You will NOT however see any space increase UNTIL you have replaced ALL drives - just the way Raid controllers work. BTW its a long process since each drive has to initialize (up to 36 hours), then disk management to expand volume and build redundancy - more hours, but kinda seamless - just go for a long long walk - like to Spain or something.

Note Note:
This is where the Drobo and ReadyNas's Xraid2 products come into play. They use a proprietary Raid solution to allow use of new space before all drives are replaced - but I don't know how this works out if you have a catastrophic failure and need your drives to be sent out for professional recovery, as they may not have access to that format and may not be able to recover these drives.

Hope that gets you started

[zeroibis]

Sorry for the confusion, I am using 4 2tb drives. So the formatted space is 4tb. I should have said that I have 8tb worth of space with 4tb after n-2 so that it would be clear what I am doing. Also I am not using an on board controller but a dedicated raid card from areca.

So from what I read I should have no problem expanding the array size. So my next question is that to take advantage of the extra 2TB I just got to load up Disk management and click extend volume? I assume this is what should happen as if I was to expand my raid the extra 2tb would be unallocated. I also assume that the extend volume function in Disk Management will not delete any data occupying the allocated space.

Am I understanding how this all works correctly or am I missing something?

Thanks again for the help

[DTR]

Am I understanding how this all works correctly or am I missing something?

Thanks again for the help

Opps forgot to add, which is good the you asked. And again, I'm speaking for the Intel ICH10R reference point....

Intel software, called Rapid Matrix or something...Requires that I go in (it lists all drives connected to the controller, in the array and others (hot spare for example). You need to select that new drive and 'ADD IT' to the array. Now you go to Disk management and expand volume.

So for your controller, you may need a similar step before it is available in disk management.

From here I think its gotta be specific to your controller - hope someone else can share step by step - took me awhile to figure it out as its not really documented at all (in Intel's case)

[zeroibis]

Requires that I go in (it lists all drives connected to the controller, in the array and others (hot spare for example). You need to select that new drive and 'ADD IT' to the array. Now you go to Disk management and expand volume.

Yea according to my manual it looks like I go to "Expand RAID Set" and then click "Select SATA Drives For RAID Set Expansion" then select the drive then press yes to start the expansion but from there I also have the option to change my RAID level and or stripe size. (which I will leave alone)

From there I guess I got to wait an hour or so for it to do the magic and then after a reboot I should see some unallocated space on the disk within windows disk management. At least this is what I am lead to believe....

[xeon_1]

i think i will take a bit longer.
I just had to wait 4 hours to reinitialise my array.
And the larger the disk the longer it takes.

[DTR]

I should mention - its smart to go Raid 6 with 2TB and up drives. There is a very high likelihood of a second drive failure DURING rebuild. Don't have the article to link to but basically, its math and MTBF. The drives have to spin and write so much data during rebuild (the entire drive) that statistically, you can cross the MTBF with larger drives.

Think about it this way, you can write a whole 100GB drive ten (10) times before you can write ONCE to a 1TB drive completely. So if the error rate is 1 in 1TB (which you'd think is pretty small), a smaller drive like the 100G will only have a failure rate of 1/10 whereas the larger 1TB drive will fail every time. Numbers used are for example simply to communicate the point.

[zeroibis]

Yea, that is exactly why I went with raid 6 so that I would be redundant during a rebuild. Also as to it taking forever yes it took almost 6 hours to initialize the array and it will be about 6 hours when it finishes the format.

Now I just got to figure out how to RMA my DOA drive (yea I actually had 5 to start but one was bad out of the box, so when it is all done I will end up with a nice 6 drive 8TB array, with open ports for more drives down the road).

[DTR]

6 drive 8TB array, with open ports for more drives down the road).

Nice....how many drives does that areca controller support?

[zeroibis]

I got the 8 drive model as that was the best I could afford. I threw over a grand on this upgrade and I hope to make it a big success, I even have fault leds taped to the back of each drive so it will be fast and easy to see which one is bad when one of them finally fails. While I do have a battery backup for my computer I may down the road save up some money and invest in the battery for the card itself for an extra layer of protection. I am glad I got so much space in my system for all of this, right now I actually have 9 drives (1 SSD, 2 15k SAS in RAID 0, 1 1TB drive, 1 2TB drive and the 4 2tb drives that are formatting right now plus another 2tb drive on the way (when I figure out how to RMA it). (on that note is anyone familiar with how to exchange a DOA drive from new egg?)

Thanks again for the help guys, I am feeling a lot more easy about this array expansion now.

[MadHacker]

i have 4 2TB drives in raid6 on a highpoint controller,
before i build/expand the array i start with testing the drives to make sure they are good.
then using the highpoint software (web based) re-size the array, it took me about 2 days to build my array, perhaps highpoint has a really slow controller, duno.
then to expand it you will need to use diskpart.exe which is a command line app.
also make sure that you are using GUID Partition Table (GPT) since it supports partitions over 2TB.

[zeroibis]

My OS is not on the array so I do not see why I would need to use a command line. Should it not just work like when you expand normally in Disk Management?

Also on another note I just finished my 12 hour long 1.7TB transfer... now to CRC check... BTW for those who move lots of stuff TeraCopy is great, it is a free app that replaces file transfer in windows. (using win 7) It allows me to know that everything transferred without error and even CRC check the files afterword to ensure there was no corruption.

[zeroibis]

Well I am all done and it was a success! Thanks for the help guys! I can not believe my speeds on this thing (over 800mb/s read and write and over 90mb/s random read+write on 4k random!)

Here is what I did so that anyone who comes across this thread can get the answer:

1) I Expanded My RAID Set to include the extra drive this took 14 hours. (adding 1 2tb drive to 4 2tb drives with stuff on the drives)

2) I Modified the Volume Set to increase the space from the current setting of 4tb to the max available of 6tb (this took 2 hours)

3) Expanded the partition in Disk Management (takes a second)

Note that I did all of this without losing files on the drive. I do not run my OS off this array and if you do then it might not work this way.

[DTR]

Well I am all done and it was a success! Thanks for the help guys! I can not believe my speeds on this thing (over 800mb/s read and write and over 90mb/s random read+write on 4k random!)

Glad to hear it !!!


PS Speeds you are getting are phenomenal...sure puts the ICH10R to shame.

[zeroibis]

Well I am all done and it was a success! Thanks for the help guys! I can not believe my speeds on this thing (over 800mb/s read and write and over 90mb/s random read+write on 4k random!)

Here is what I did so that anyone who comes across this thread can get the answer:

1) I Expanded My RAID Set to include the extra drive this took 14 hours. (adding 1 2tb drive to 4 2tb drives with stuff on the drives)

2) I Modified the Volume Set to increase the space from the current setting of 4tb to the max available of 6tb (this took 2 hours)

3) Expanded the partition in Disk Management (takes a second)

Note that I did all of this without losing files on the drive. I do not run my OS off this array and if you do then it might not work this way.

Thank God I wrote this down, now to follow my own instructions to add another 4tb lol.