Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

Upgrading a 3-disk RAID5 with an extra HDU - is data integrity retained?

Posted on 2013-05-27
2
Medium Priority
?
629 Views
Last Modified: 2013-05-28
Hi,

I have a client with a HP Prolaint with a RAID5 configuration with 3 146GB disks. They have some problems with data usage and they want to expand the storage. Now someone has advised them to add one 146GB harddisk, and they claim that the data integrity will not be changed.
The client assumes that the 4th harddisk will be aded to the RAID5 config. If this can be done, he will not have a nett storage of 146GB but less, am I right? And is this a save sollution?

Thnx for your imput.

Grtz,

Erwin.
0
Comment
Question by:Erwin in de Braekt
2 Comments
 
LVL 10

Expert Comment

by:rjanowsky
ID: 39200449
Have look at this thread concerning RAID expansion at the HP Communities. You can also check this HP Reference Guide for Array Configuration. Array expansion is possible, if some preconditions are met. And you are right, that not the complete capacity will be usable, because the RAID5 needs some space for redundancy.
0
 
LVL 56

Accepted Solution

by:
andyalder earned 1500 total points
ID: 39200724
Parity is maintained during expansion, it re-stripes from 3 disk RAID 5 to 4 disk RAID bit-by-bit* and keeps track of the progress using the battery backed write cache. Normal write cache is disabled during the expansion since the cache is used in the re-leveling process, you can even have a power outage half way through and because of the cache it will pick up again where it stopped. You should still backup first just for safety and continue with your normal backup regime during the expansion, it does take a long time but the server is still usable during the process. You can change the expansion priority using the ACU to make it expand faster at the cost of reduced performance.

He will have the full 146GB extra space (taking 146GB as 146000000000 bytes) since one disk worth of space is used with RAID 5 whether 3 or 4 disks in the array. The extra space won't be added to any logical disks you have but you can expand the current logical disk or create a new one after the expansion is complete.

*It may be that it does a single full-width stripe at a time or it may do several at once, I'm not sure about that.
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The question appears often enough, how do I transfer my data from my old server to the new server while preserving file shares, share permissions, and NTFS permisions.  Here are my tips for handling such a transfer.
New style of hardware planning for Microsoft Exchange server.
This video teaches viewers how to encrypt an external drive that requires a password to read and edit the drive. All tasks are done in Disk Utility. Plug in the external drive you wish to encrypt: Make sure all previous data on the drive has been …
Despite its rising prevalence in the business world, "the cloud" is still misunderstood. Some companies still believe common misconceptions about lack of security in cloud solutions and many misuses of cloud storage options still occur every day. …
Suggested Courses

916 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question