Mat sent me an e-mail this morning, asking “why would FAST Cache be degraded after losing B0 E0 D2 in one of the CX4-960s?”. For those of you playing at home 0_0_2 is one of the Vault disks in the CX4 and VNX. Here’s a picture of the error:
Image may be NSFW.
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Check out the 0x7576 that pops up shortly after the array says there’s a faulted disk. Here’s a closeup of the error:
Image may be NSFW.
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Weird, huh? So here’s the output of the naviseccli command that will give you the same information, but with a text-only feel.
"c:/Program Files/EMC/Navisphere CLI/NaviSECCli.exe" -user Ebert -scope 0 -password xx -h 255.255.255.255 cache -fast -info -disks -status Disks: Bus 0 Enclosure 7 Disk 0 Bus 2 Enclosure 7 Disk 0 Bus 0 Enclosure 7 Disk 1 Bus 2 Enclosure 7 Disk 1 Bus 1 Enclosure 7 Disk 1 Bus 1 Enclosure 7 Disk 0 Bus 3 Enclosure 7 Disk 1 Bus 3 Enclosure 7 Disk 0 Mode: Read/Write Raid Type: r_1 Size (GB): 366 State: Enabled_Degraded Current Operation: N/A Current Operation Status: N/A Current Operation Percent Completed: N/A
So what’s with the degraded cache? The reason for this is that FAST Cache stores a small database on the first 3 drives (0_0_0, 0_0_1, 0_0_2). if any of these disks fail, FAST Cache flushes to disk and goes into a degraded state. But it shouldn’t, because the database is triple-mirrored. And what does it mean exactly? It means your FAST Cache is not processing writes at the moment. Which is considered “bad darts”.
Image may be NSFW.
Clik here to view.
This is a bug. Have a look on Powerlink for emc267579. Hopefully this will be fixed in R32 for the VNX. I couldn’t see details about the CX4 though. I strongly recommend that if you’re a CX4 user and you experience this issue, you raise a service request with your local EMC support mechanisms as soon as possible. The only way they get to know the severity of a problem is if people in the field feedback issues.
