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Changing RAID configuration for some drives

 
Ross76
Occasional Visitor

Changing RAID configuration for some drives

One of our customers has a Proliant DL380 G3 server with six 73-GB SCSI hard drives. The IT Manager told me that initially this server had 4 drives only in a RAID5 configuration (Array A), he then added two more drives early this year and now there are 2 logical units in a RAID5 configuration. The Array Configuration Utility 7.40 says:
Logical Unit 1 (208378 MB, RAID 5)
Logical Unit 2 (138919 MB, RAID 5)

It seems the two additional drives have merged into the first RAID configuration, I find it confusing.

Anyway, the problem is: the IT Manager wants to get more HD space and wants to get rid of those two drives. He just bought two new 146-GB drives and wants them in a RAID1 configuration.

According to the ACU, if I replace the last two drives with the bigger ones at the same time I should lose everything. Is that right? How can migrate from that (messy?) configuration to a configuration with 4 drives in RAID5 and 2 bigger drives in RAID1???

Thank you.
8 REPLIES
chongkan
Trusted Contributor

Re: Changing RAID configuration for some drives

Hi, Ross

mmm, It is confusing:

1st Logical drive should be:

4*72.8 GB - 1*72.8 = 218.4, you have 203.4 GB

2nd Logical drive should be:

*By the way there's no way to make a raid 5 with less than 3 logical drives...

2*72.8 - 1*72.8 = 72.8, you have 135.6 GB, thinking on a Raid 1

It just doesn't match...

Open ACU again, in the middle colum, on the top right of that colum, it says "Show Physical view", click it and you'll see how many HDDs does each Logical Drive has.

Now, from what ever RAID configuration you're migrating from, what you have to do is:

Go to ACU and set rebuild priority to high, select the controller, go to the option at the right column and set it to high, if setting extend priority to high too is allowed, do it at this point. Save changes.

At this point you have to decide: Would you like to this process online ( slower ) or offline ( faster )?

Online could be done by ACU over Windows so the server can stay up but the overall performance will be degraded and the process could take more than 1 day or more depending on the servers utilization.

The offline process could take up to 2-4 hours or less cause all resources are being use to complete the process.

1- Always use drives with the same size in the same RAID to avoid loosing the "extra" space..
2- Replace one drive at the time and let it rebuild completely. ( Until the green arrow on the drive stops blinking )
3- once all drives has been replaced and all rebuilds have taken place, go to ACU, select the controller, select option or properties, look for and extend the old logical drive to use all available space.
4- Once extended, use Partition Magic Offline to to expand the logical volume..
5- There are some issues expanding the System volume with Diskpart, search "fsextend.exe" on google.
6- Search "diskpart.exe + download" on google to find teh utility.

Regards.


Ross76
Occasional Visitor

Re: Changing RAID configuration for some drives

Thank you for your reply. I'm going to add the new drives tomorrow and that configuration is really confusing me.

The Physical View in the ACU says:
72.8 GB SCSI parallel Unit in Port 2 : ID SCSI 0
72.8 GB SCSI parallel Unit in Port 2 : ID SCSI 1
72.8 GB SCSI parallel Unit in Port 2 : ID SCSI 2
72.8 GB SCSI parallel Unit in Port 2 : ID SCSI 3
72.8 GB SCSI parallel Unit in Port 2 : ID SCSI 4
72.8 GB SCSI parallel Unit in Port 2 : ID SCSI 5

It seems like the two last drives have merged into the first RAID5 and they have something in common. I know I need to move everything from there (I can see them as 138 GB partition in Windows 2003 Server) and replace them with the bigger drives and create a new RAID1. I'm wondering whether the first 4 drives would be affected by the upgrade.
sandeep_raman
Honored Contributor

Re: Changing RAID configuration for some drives

Hello Ross76,

If these are true,

1.The existing additional disks are part of a different array(array B)
2.It has data only and not a system partition

then,you could try these options.

1.Pull out one of the 72Gb disk and add the 146Gb disk and wait until it rebuilds.
2.Once rebuild is complete,pull out the other 72Gb disk and plug the 2nd 146gb disk,wait for rebuild to complete.
3.Use diskpart to extend the logical volume.

SRH
Ross76
Occasional Visitor

Re: Changing RAID configuration for some drives

Yes, I have just come to the same conclusion. The first 4 drives were members of a logical Unit in a RAID5 configuration. The additional drives became members of the same array but under a different logical Unit. So, there are almost 350 GB available in two different logical units (208 GB + 138 GB). If I delete the second logical unit (and its drives), I shouldn't lose the first logical unit and its four members.
Caster Troy
Regular Advisor

Re: Changing RAID configuration for some drives

exactly pull out the 72.8GB and insert the 146.8GB, wait for rebuild to complete (if neccessary set priority to high) then perform same with the 2nd 72.8GB and wait for rebuild. extend logical partition and all done.
Evil Has Its Winning Ways
Stephen Kebbell
Honored Contributor

Re: Changing RAID configuration for some drives

Wait, hold on.
It looks like all 6 disks are in one physical array (Array A). It looks like when they went from 4 to 6 disks, the array was expanded, and a new logical drive was created. This means each logical drive is spread across all 6 disks. There would be no way to migrate online to 4 Disks in RAID5 and 2 in RAID1. You would have to delete the array, and start from scratch.
Replacing just 2 disks with 146GB ones will not help one iota. The array will only use 72GB of each disk, wasting the capacity.

Can you post a screenshot of what ACU displays? (logical and physical)

Regards,
Stephen
kris rombauts
Honored Contributor

Re: Changing RAID configuration for some drives

Ross,

Stephen is absolutely correct, your 6 drives are simply part of one RAID 5 array but the new free space that became available after 2 new disks were added has been used to create a secondary logical drive.

Their is no way you can revert back from the 6 drive to a 4 drive RAID5 array, even if you delete the 2nd logical drive, if you rmeove the 2 disks again, your raid5 array is dead and all data is lost.

Do not use the 146 Gbyte disks to replace the 73 Gbyte ones, you will simply end up with the same issue and have new free space in which you can create a third logical drive but no raid1 independent mirroring, everything will still be part of the same RAID5 array.

Kris
chongkan
Trusted Contributor

Re: Changing RAID configuration for some drives

If you replace any 72.8 GB drives with a larger drive, the SA-C will only recognize the smallest drive size on the array from each drive, so you'll end up havind the same space.

Anyway, you already have 136.5 GB as second logical drive, and you want to use 2 x 146 GB drives in RAID 1 instead of what you thought was a separated RAID 5, that would be mmmm ufffff like 10GB more!!!

Resolution:

Get 2 x 300 GB for RAID 1 = 300 GB
Back up data, reconfigure RAIDs, re-install OS and restore Data.

I'm sorry dude..