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How can I increase disk space on a RAID 5 server with no slots left?

Posted on 2011-09-16
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Last Modified: 2012-05-12
I have an HP DL380G5 with (8) 146G drives in a RAID 5 configuration.  My OS is Windows 2008 Enterprise and I have 4 virtual machines with the VHD files stored on the drives.  I am currently running out of space on the array and need to increase the size of the drives.  Since I have no expansion bays, I was wondering...can I replace the drives, one at a time, with 600G drives, letting each one rebuild before installing another, until all 8 slots are populated with the new drives?  TIA for any suggestions.
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Question by:ty_young_99
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18 Comments
 
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Expert Comment

by:davorin
ID: 36552579
Yes, it can be done, but having 8 drives in one raid 5 is a little bit risky.
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Expert Comment

by:John Hurst
ID: 36552614
In my experience, the drives will still wind up as 146Gb drives (one by one). At least on Server 2003 with hardware RAID 5, you cannot increase drive space with bigger drives. ... Thinkpads_User
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Expert Comment

by:John Hurst
ID: 36552652
ty_young_99: It would probably be much easier (but a bit more expensive) to add a Storage Server to your network. Server 2008 can act as a Storage Server - I have one running at a client and the purpose was to add disk space.
... Thinkpads_User
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Author Comment

by:ty_young_99
ID: 36552655
That what I was afraid of.   I guess that's my real dilemma. Does the HP ACU let you take advantage of the additional space after the drives have been installed?  Otherwise its all in vain.
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Author Comment

by:ty_young_99
ID: 36552661
Yeah, storage server's out of the question.  I have good backups and all, but restore from tape takes forever.  Good for disaster or recovering a few things but not a Terabyte.
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Expert Comment

by:John Hurst
ID: 36552662
The RAID controller will build to the original limit and the rest of the space is just wasted. No system would ever know about the additional space because it is not registered to anything. ... Thinkpads_User
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by:John Hurst
ID: 36552664
If a storage server is out of the question, you may need to buy a new server with much more space to begin with. Also, if doing that, plan for yet more space down the road.  ... Thinkpads_User
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Expert Comment

by:gamesaregood
ID: 36552753
As already advised you can't expand your existing raid 5 array. Have you considered adding a Direct Attached Storage solution to the server?
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Author Comment

by:ty_young_99
ID: 36552770
I think I may have found my answer in another posting titled INCREASE RAID 5 SIZE.  According to Compaq Engineer, this can be done and sharkbot221984 actually did it successfully.  Now all I need to know is how?
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davorin earned 500 total points
ID: 36553631
Please look at P400 user guide at page 29 at Upgrading hard drive capacity:
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00572169/c00572169.pdf

As I said it is possible.
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by:davorin
ID: 36553641
You will also need this user guide - look at page 35 at Extend Logical Drive
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00294139/c00294139.pdf

So replace all drives one at time, every time wait for rebuild to finish, extend the logical drive using ACU, expand or create new partition in windows 2008 server
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by:davorin
ID: 36553642
Sorry typo - Extend Logical Drive is on page 25.
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by:andyalder
ID: 36554583
You can certainly replace one at a time and finally realise the extra space but look at how long you will be without parity. It used to be a useful option with 9GB, 18GB disk sizes as rebuild was fairly fast, but with 146GB disks you're talking at least a day to rebuild each time so the chance of encountering a disk failure or bad block increases. Can you afford a couple of weeks with the extra risk of effectively having RAID 0?

I'd be more tempted to add a MSA 50 or MSA70 external shelf plus P800 controller, you can move the cables from the current controller to the P800, then you have the 8 internal plus 10 (or 25) external bays to play with. Since the MSA50, MSA70 and P800 have been superceded with a new generation you could buy quite cheaply.

About $350 for the controller, and $600 for the enclosure off ebay, may be second hand but not like you're buying second hand disks, the shelf works or it doesn't so doesn't matter that it's not brand new.
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Author Comment

by:ty_young_99
ID: 36555396
So why is having 8 drives in one RAID 5 risky?
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by:andyalder
ID: 36555676
The more drives you have in one RAID 5 array the more chance of a second disk failure during a rebuild, also the higher the capacity of those disks the more chance of an unrecoverable read error on a disk during a rebuild. The controller does check it can read the drives properly and repairs any read errors during background parity check but that's only when it's idle. It would be safer to use RAID 6 (ADG), then you can suffer two drive failures without it crashing, but the performance is worse than RAID 5 and you would have to buy the Smart Array Advanced Pack and possibly a larger cache module to enable RAID 6.
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Expert Comment

by:davorin
ID: 36555965
And when you buy a server, frequently you get disk drives from the same series. I had cases when two drives from same series failed soon one after another. That is why I do not use single RAID5 array on more than 5 drives.

The need of upgrade depends on controller model you have. HP DL380G5 comes with this three models. Only the first one supports RAID6 as it is.
- Performance Models: HP Smart Array P400/512MB BBWC Controller (RAID 0/1/1+0/5/6)
- High Efficiency and Base Models: HP Smart Array P400/256MB Controller (RAID 0/1/1+0/5) - Available upgrades: 512MB battery-backed write cache (BBWC) or standalone battery for RAID 0/1/1+0/5/6
- Entry Models: HP Smart Array E200/64MB Controller (RAID 0/1/1+0) - Available upgrades: 128MB battery-backed write cache (BBWC) for RAID 0/1/1+0/5
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Expert Comment

by:andyalder
ID: 36556142
You're right, it's the P410 that needs advanced license for RAID6, not P400.
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Author Closing Comment

by:ty_young_99
ID: 36558076
This is great, it's just what I was looking for.  Thanks for all your help and for the advice as well.
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