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RAID 10

Last response: in Business Computing
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May 8, 2012 2:34:32 PM

Hi everyone,

First post over here, i hope you can help me.

I just begin a new work and they have a SBS 2011 server in RAID 0.

The things is the server is a File Server, Active Directory, DHCP, DNS, Exchange 2010 and he support a home application. And If one of the HD crash, the business will be off for one or 2 day maybe more, the time i order a new HD and do a disaster recovery. And of course i will be the guy why nobody can work.

Thats why i prefer to be proactif than reactif


The 2 actual HD is HP SAS Modèle: HP EF0600FARNA

What i want to do (If possible) its buy 2 new SAS HD. Create a RAID 1 with the new HD. Transfert everything on the new RAID 1.

Take the RAID 0 and create anoter Raid 1 and then create a RAID 10 with the 4 SAS Drive.

Of course i will create a backup of everything before doing anything.

I just wondering if its technicaly possible to do that in this way? And if a can transfert everything between a Raid 0 to a Raid 1 without losing all my configuration. I will not do that in the business hour of course.

And when i create the raid 10 did he erase everything on the 4 HD?

Thanks for your help and advise.

(sorry for my english not my first language)

More about : raid

May 8, 2012 2:46:16 PM

Does your server support RAID 10? You will need to backup all of the data and restore it to the new RAID 10 drive. I haven't seen a RAID card that allows you to add a mirror to an existing RAID 0 array.
May 8, 2012 2:53:33 PM

Try mdadm, software raid. You can add disks and change raid configuration easy.
Related resources
May 8, 2012 3:04:01 PM

Smart Array P410i

RAID Support RAID 6, 6+0 (Advanced Data Guarding)
NOTE: RAID 6, 6+0 can be enabled with either

Minimum of 256 MB cache, Battery kit and Smart Array Advanced Pack License key option upgrades

Minimum of 512 MB BBWC/FBWC and Smart Array Advanced Pack License key option upgrades


RAID 5, 5+0 (Distributed Data Guarding)
NOTE: A minimum or 256 MB cache and battery are required to enable RAID 5, 5+0 support of the Smart Array P410i
RAID 1+0 (Striping & Mirroring)
RAID 0 (Striping)


Yes Its supported.

I will take a look of mdadm

Thanks
May 8, 2012 3:23:01 PM

You will probably have to build it from scratch and backup all of the data.

The way RAID 10 works is that it makes a RAID-1 from two RAID 0's or vise versa. So you would get your 2 new HD's and then setup a second RAID 0. From there, you would have two separate RAID 0's, then you would use the software to create a RAID 1 across them. This will mean that the original RAID-0 is replicating onto the new RAID-0.

With 4 hard drives, I would recommend a RAID5. It doesn't sound like the business is very large or the exchange server is very large either. In a larger environment, I would recommend a different server for exchange with multiple disk groups setup appropriately for the database and log files, but this isn't the case here.

Are you in need of space? If not, I would set them up as a RAID 5 with a hotspare. You'd have the same space as before, but with multiple layers of redundancy. In fact, you would have more redundancy than with the RAID10. Any 2 of the 4 drivers can fail with this setup and there will be 0 downtime. You could order 2 new drivers and hotswap them instantly. With the RAID10 setup, if the wrong 2 drives were to fail, the raid would fail.

If you needed space, then you could forget the hotspare and go with the RAID5, which will still give you disk parity.
May 8, 2012 5:13:37 PM

Thanks for the answer

Actually in RAID 0 with 2 600Go we have 1200Go of space available. And its enought. The first reason why they install it a Raid 0 its for the write effiency.

With a RAID 5 we will have a 1800Go with a hot spare. If we have a disk crash we can do a recover on the spare.
If we loose 2 Drives we're "/$"% no?
Do we have loose any time by the recover on the spare?
And we loose some write speed right?

RAID 10 also with 4 600GO we keep 1200GO avaible but we increade the write speed and we have redundancy who allowed to loose 1 HD without direct effect.
If we loose 2 drive depend on wich Raid 0 its a disaster recovery

You right its not a large business.

May 8, 2012 6:15:10 PM

Right, with the RAID 5, you'll have both a parity drive and a hotspare, so if you lost 2 drives, your system would still continue to run.

Basically, out of the 4 drives:

1 Data drive
1 Data drive
1 Parity drive
1 hotspare

technically, its not one individual disk that holds that parity data, but you can look at it the same way. So if one disk dies, the RAID will automatically rebuilt onto the hotspare using parity data. If 2 disks die, the system will continue to run off parity data until you replace the raid. It would take 3 disks to completely lose all data.

In my opinion, that's the best bang for the buck, tons of redundancy, you still keep fast striped speeds (not quite as fast as RAID 0 but faster than RAID10).

So yeah, go buy 2 600GB disks. BACK UP YOUR DATA. Then create a RAID 5 array out of 3 of the disks. Then assign the last disk as a global hotspare. All can be accomplished in the POST RAID utility during boot.

But make sure to backup everything onto another disk, like a 2TB external storage unit. If you have an imaging utility, this could work, but I would personally backup the data, then reload windows and rebuild everything from scratch, such as AD users, policies, etc.
May 9, 2012 1:50:52 PM

^ +1 well said
May 9, 2012 2:04:55 PM

cirdus can you clearify one thing, my understanding is that raid 5 can only recover from 2 disk failure if it had successfully rebuild onto the hot spare, otherwise say if both data drives failed without a chance of rebuilding you still can't recover from parity drive alone.
May 9, 2012 2:07:45 PM

zhihao50 said:
cirdus can you clearify one thing, my understanding is that raid 5 can only recover from 2 disk failure if it had successfully rebuild onto the hot spare, otherwise say if both data drives failed without a chance of rebuilding you still can't recover from parity drive alone.


Actually you are correct. cirdus is correct, as long as the hotspare had time to be built (as you just said). RAID 6 is the solution needed to sustain 2 drive failures at the exact same time.
May 9, 2012 3:19:11 PM

How does a RAID 6 array differ from a RAID 5 array? I am a little confused on that one.
May 9, 2012 3:34:40 PM

choucove said:
How does a RAID 6 array differ from a RAID 5 array? I am a little confused on that one.


http://en.wikipedia.org/wiki/RAID

Basically, RAID 5 uses 1 parity drive. 6 uses 2 parity drives. 5 allows for 1 drive to fail, 6 allows for 2 drives to fail simultaneously.

Regardless of RAID type, Hotspare(s) allow for for additional failures ONLY after the hotspare has been built-into the array after the initial failure.
Example: In a RAID 5, if a drive fails, and the hotspare is in the process of being built yet another drive in the original array fails, data lost.
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