Discard Preserved Cache

Question

We had faulty disk in RAID-0 and had to replace it.
New disk is now Ready (as you can see below through iDRAC)

We need to add a new Virtual disk volume named "Virtual Disk 3" as replacement for this new disk

I did then create virtual disk (named "Virtual Disk 3") | Advanced Configuration | then selected same settings you see for other disks (No Read Ahead, Write Through) then finally click "Add to Pending". I get error below.
I am not clear what to do from here, the disk is new, why would I recover anything fmor the pinned cache ?

I am not sure but I guess I need to select action "discard preserved Cache " on Controller through iDRAC as you see below. Is it correct ? This is a production server so, not sure about this step, need confirmation that it will not delete/change anything for the other RAID-0 disks or change the RAID-1 boot one ? Can anyone confirm that this is no risk ?

Dell-DylanJ · Accepted Answer

Hello,   Yes, you'll want to go ahead and discard the cache. The cache is specific to the old virtual disk, so this won't affect other volumes.

Moaeyd · Answer

HiI have done discard the cache but I am still not able to do a Raid, knowing that I am using IDrac 9 and since I have done discard the cache from Controller Configuration according to the picture..Note: I do not know how to determine which hard drive I have discard the cache on, and it does not show me discard the cache as in the picture sent by Solmil.

DELL-Erman O · Answer

Hello, normally you can create RAID via iDRAC.

to identify your VD

To determine which hard drive you’ve modified, follow these steps:
- Log in to iDRAC 9.
- Navigate to the virtual disk configuration.
- Look for the specific virtual disk you worked on (e.g., RAID 5).
- View the member disks associated with that virtual disk.

In the iDRAC Web Interface, go to Configuration and then click Storage Configuration.
Go to Storage and then click Physical Disks.
Select the RAID controller for which you want to create the virtual disk from the Controller drop-down menu.
Check that available disks are listed in the Physical Disk Configuration section.
Open the Virtual Disk Configuration menu and click on the button Create Virtual Disk.
The creator wizard appears to configure the Virtual Disk properties. In the Capacity field, enter the size of the virtual disk.
Click Add to Pending Operations when ready.

But if you can't do it on iDRAC then you can use the PERC BIOS interface.

Accessing the PERC BIOS Configuration Utility:
- During server startup, you’ll need to press CTRL+R
  - For PERC Series 7, 8, and 9:
    - In BIOS mode, press Ctrl+R.
    - In UEFI mode, press F2 to enter System Setup.
    - Navigate to the Device Settings within the System Setup Main Menu.
  - For PERC Series 10 and 11:
    - In UEFI mode, press F2 to enter System Setup.
    - Navigate to the Device Settings within the System Setup Main Menu.
Discarding the Cache:
- Once in the configuration utility:
  - Look for an option related to “Preserved Cache” or similar.
  - Choose “Manage Preserved Cache” from the menu.
  - Execute the action to discard the preserved cache.
- Confirm that this action won’t affect other RAID volumes.
- The cache will be deleted from the PERC, allowing you to create a new virtual disk if needed

Hope that helps!

PowerEdge HDD/SCSI/RAID

Discard Preserved Cache

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