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ProLiant Servers (ML,DL,SL)
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Adding Storage Space

Greg D Johnson
Occasional Visitor

Adding Storage Space

I have a ML370 with 3 empty slots for HDD.

The exiting RAID contains 3 HDD in a RAID 5 config.

Can I simply add three more (or 1 or 2) drives to make it larger? Or should can I create a seperate RAID array with three new drives.

Smart Array 641
Compaq Wide Ultra3 SCSI Adapter
OS Windows 2003 SP2 SBS

What more info can I provide to make my question clearer.



P.S. This thread has been moved from Servers --> Net Servers to Servers --> Proliant (ML,DL,SL), Forum Moderator


Re: Adding Storage Space

The SA641 and other Smart Arrays with Cache memory support expansion of existing arrays. Disks are hot swappable, so you just need to insert the disks 1 by 1, and once they are available you should be able to create a new array or grow the existing one using ACU in windows.

Remember to back up the data just in case (array expansion and lun extension take 15 min/GB). And make sure the expansion priority is set to a level that works for you, this will have direct impact on the performance hit during the expansion and the time it will take to finish.

As a best practice, make sure FW and drivers are up to date before expanding.

Once you have the disks detected in the controller, you should have the option to Expand the array or create a new one.

Once the array is expanded, you can then extend the Logical Unit (or create a second lun in the array). After the lun is extended, the last step is growing the partition with an application such as Diskpart (free with Windows) or a similar program.

Check the ACU user guide page 24-25 for more info:

Greg D Johnson
Occasional Visitor

Re: Adding Storage Space

Thanks for the quick reply. I think, if I understand you correctly, I can add one additional drives to the existing array.

We are going to be getting them a new server toward the end of the year, so if I add that drive in right now, I think it will suffice.

How much do you think performace will be affected?

Re: Adding Storage Space

The idea is to make sure all the new drives are seen as available in ACU, once that is done you can expand the array one single time using the 3 disks at once if that is what you need. About the performance hit, I dont know a specific number for it, that is why it is good to make sure the expand priority is set correctly, if you set it to low, IO requests will be handled pausing the expansion process, on the other end High priority will handle IO requests while doing the expansion, medium is in between, so a higher priority will make the expansion faster but performance can be more impacted; take into account the RAID 5 should be able to maintain redundancy in the event of disk failures but no one would like a disk failure during a expansion process and the faster it finishes the better, so I would recommend you to use medium or high. Downtime is not required, but it would be a good idea to start the expansion in a time that you expect low IO requests, and let it do the job.
Greg D Johnson
Occasional Visitor

Re: Adding Storage Space

Thanks. I was planning on doing it after hours as I know from just replacing a drive within an existing array performance takes a hit. Thanks for all your help!