Tag Archives: Array

HP MSA P2000 (G3) Error – ‘Unwritable write-back cache data exists for a volume’

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KB ID 0000817 

Problem

Seen on a G3 P2000 SAN, the client had also had an MSA70 shelf, which contained a failed array. I was removing the MSA and after the job, this error was getting logged.

Unwritable write-back cache data exists for a volume (vdisk: unknown name, volume: unknown name, SN {Serial Number} it comprises {number}% of cache.

Solution

Essentially, there was data in the cache that needed writing to the array/vdisk, when it failed. If the volume was going to get repaired and brought back online the data would have got written back. However this volume was never coming back.

1. Connect to a controller via Telnet.

2. Issue the following command;

[box] clear cache [/box]

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Dell PowerEdge – PERC RAID Card Importing / Using ‘Foreign’ Disks

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KB ID 0000639 

Problem

I bought some SAS disks from eBay to go in my Power Edge 2900 Server, and scratched my head for a while trying to get the PERC RAID controller to use them. I could only see them marked as ‘Foreign’. Probably because they did not have their original config ‘wiped’ off them before I bought them.

Solution

1. Boot the server, Press CTRL+R when prompted, then press ‘C’ to enter the Configuration Utility.

WARNING: DONT clear the config on the controller or you lose ALL your Virtual Disks / Arrays.

2. Select the controller > F2 > Foreign Config > Clear > Confirm.

3. You can now add the disk(s) as a new Virtual Disk.

4. I’m just presenting one 300GB SAS disk as RAID0 here.

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