Hi there!
We had a problem with a Dell Poweredge R710 that uses a Perc H700 Controller. A little background, sorry if this is too long, I’m going to put a TL DR at the end.
Disks 0 and 1 were flashing orange in front panel. We did not have any info on IDRAC 6, it’s too old and would not show us any Storage details. I didn’t have ANY info on other disks or Virtual Disks, so we had to shutdown the server and check directly in the Controller Menu.
Turns out the Virtual Disk 0 that had both faulty disks was a RAID 5 that, for me, was a 4 disk array. Someone said it was a 3 disk array and I strongly disagree. Here are the evidences:
Evidence 1 - VD Management page showed 4 lines below Virtual Disk 0, with one line as “Missing”. There was a SATA disk in bay 2, but the Volume was configured with SAS disks. So I assume someone incorrectly replaced the disk. If the volume was supposed to have 3 disks, there wouldn’t be a “missing” line there. It does not make sense, there is another 2 disk Virtual Disk using bays 4 and 5, and it shows exactly both disks there.
Evidence 2 - Immediatly after I plugged in a SAS disk in bay 2, the RAID started rebuilding automatically. This indicates this bay was used for this volume before. If bay 2 was not used before for this Virtual Disk 0, the disk would not be adopted automatically. It would be “Ready” or “Foreign”.
Evidence 3 - The size of the Volume is around 1600GB. All 3 present disks are 558GB. Raid 5 total space is calculated like this: Total Space = (Number of disks -1) x Size of smaller disk. So, it would be IMPOSSIBLE for this to be a 3 disk array inittially.
Am I missing something here? For me, we actually saved the Server. If the RAID was a 4 disk array and number 2 was already offline, then removing disk number 0 or 1 would have killed the server. Just because bay number 2 leds where all green, it does not mean the volume was safe. This LEDs indicate disk health, not volume health.
Someone said that Perc H700 could automatically adopt a disk IF it had a RAID in emergency state, but I never heard of this. Yes, we can use OCE (Online Capacity Expension) to upgrade the number of disks, but this is not done automatically.
TL DR: Given the 3 evidences, was this a 3 or 4 disk array?
Thanks everyone and sorry for the long post.
