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10376
January 25th, 2018 08:00
PowerEdge r720 Perc Raid Controller Foreign Disk
ISSUE
I have a Dell PowerEdge r720 rack-mounted server. The server has 4 drives and the raid has been set up as a RAID 6.
While on a site visit, I was told that one drive went bad and needed replacing.
- The Tier 1 techs had already pulled out the bad drive before i arrived (Disk 1).
- Upon arrival, I inserted a new drive into Disk 1. The drive started to blink fast and appeared to automatically be rebuilding. I also noticed they other disk were all fast blinking green (0,1,3). Disk 2 stayed solid green.
- Next morning, i rebooted the server and entered the Raid controller BIOS. I then found that the raid was in a degraded status and that Disk 2 was in a "Foreign" State.
At present, disk 0,1,3 are in a RAID 6, however disk 2 is in a "Foreign" State. My assumption is that the Tier 1 support pulled disk 2 out and may have tried to swap with disk 1.. Or at the very least they pulled out disk 2 - which is causing the foreign configuration state.
I have reviewed the foreign configuration and it is what they had before to the best of my knowledge, but i am not certain that DISK 2 and Disk 1 are in the original positions.
QUESTIONS
1. What will be the impact if i clear the foreign state of disk 2? Also, once the disk goes to "Ready" state, is it possible to bring Disk 2 back into the VD that is already created.
2. What will be the impact if i import the foreign state of disk 2 and the disks are not in the exact same position as before?
Thank you all for your responses.
Lawrence
Daniel My
12 Elder
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6.2K Posts
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January 26th, 2018 07:00
Setting it as a hot spare should be the last step you need to perform. As soon as you set it as a hot spare it should start rebuilding. It can take several minutes for management applications like OpenManage to report the drive status changing from "ready" to "rebuilding".
You should have two options on most of our controllers for a hot spare, global and dedicated. A dedicated hot spare is assigned to a virtual disk. A global hot spare will rebuild into any virtual disk on the controller. If you want the hot spare to only be used by a specific virtual disk then you can use dedicated hot spare to assign it to that virtual disk.
You can find a link for storage manuals on our PERC page. The manual for the PERC should contain more information about the available tasks.
https://www.dell.com/perc/
Thanks
Daniel My
12 Elder
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6.2K Posts
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January 25th, 2018 12:00
Hello
If the virtual disk is online and the data is accessible then you should not import. An import attempts to bring the drive online into the virtual disk. If the virtual disk is online then the import should fail, but if something goes wrong and it does bring the drive online then it will corrupt the virtual disk.
If you clear the foreign configuration the drive should go to a ready state. You can then use whatever options the controller supports to start a rebuild. The easiest method to initiate a rebuild is typically to set the drive as a hot spare.
Position doesn't matter with any controller supported on the R720. The controllers reads from and stores data describing the virtual disk on each disk drive. Putting drives in different slots is only an issue with older controllers that would only read virtual disk information from the first drive or the designated primary drive. I'm not aware of any of our SAS controllers that have this problem. Our SCSI controllers had this limitation.
Thanks
Lawrence4532
3 Posts
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January 25th, 2018 21:00
Hi Daniel,
thanks for the quick and concise reply!
Yes - they VD is online and the data/OS are functional.
1. Can you give me some more details on how to bring disk 2 back into the VD after i convert it to a hot spare. My main concern is keeping the current array intact. I just want to be clear on bring it back into the VD.
From your previous post and my min exposure I assume: After I clear the foreign config the disk will come to a ready state. From there i will be able to convert it to a hot spare which will allow me to add it back into the current array bring it "online" again. Is that about right?
2. What is the difference between a Global Hot Spare and a regular one? As I'm thinking it may only give me the option to make it a global hot spare ( based off another system im working with, i also maybe getting it confused with something else i saw).
Thank you,
Lawrence