i believe this is a known issue depending on the level of your FLARE code. the warning should not prevent you from completing the RG creation.

You can create a RAID10 group using disks from that enclosure and another, but If you create a RAID Group with drives from BUS 0 ENCL 0 and any other enclosure you run risk of data corruption in the event of a power loss. This is because the drives in BUS 0 ENCL 0 are powered through the SPS which will keep the enclosure online long enough to shut the array down gracefully in the event of a power failure. So some of the disks will be offline for that RAID Group during a power failure.

Since you are creating a RAID10 group with half the disks in one enclosure, and half in another enclosure, you are minimizing the possibility of data loss in the event of a power outage (whereas if you were using RAID5 you would lose data). But I would think you are still at risk and you would be better off to use drives from another enclosure.

For example, if you take one disk from bus 0 enc 0 and one disk from bus 0 enc 1 (creating a R10), you have one disk in the first DAE - this disk is powered by the SPS. If you lose power, the SPS will keep bus 0 enc 0 powered on until the cache is dumped to disk. But the disk in bus 0 enc 1 has lost power and has shut down. If there was a write in flight to the disk in bus 0 enc 1, you do not have any way to determine if the write completed or not. When this occurs the state of the raid group is now unknown and on power restore, the raid group will need to be re-built - this is for Raid 1/0.

glen

Thanks for the example Glen, based on that I would not even try and use a RAID10 group with half of the disks in bus 0 encl 0. The risks are too great.

Thanks guys for the response.

I get an alert when choosing disks from ex Bus 0 Encl 1 and Bus 1 encl 0 and so on,so I guess I can just ignore the alert for RG creation but make sure our Data center doesn't loose power at any time.

Thanks Glen and Aran for your suggestions on creation of RG 1+0.

so what happens if you create a striped MetaLUN where one of the components reside in RG on B0E0, data loss ?

I would think massive data loss

That would be like a RAID5 group losing more than one drive at a time right?

Uh-oh, i have a component LUN in RG on B0E0 . While we have datacenter UPS and generators ..i am not taking any chances, Lun migrator to the rescue (too bad we can migrate component LUNs only). Now if this is a planned shutdown of CX4, array is still getting datacenter power ..it should be fine ?

I would think it would be fine because in a planned shutdown you switch off power using the SPS power switch which prompts the array to start the shutdown process. This will power down the SPE and B0E0. Even though the remaining enclosures attached to the array are still powered up, they are dumb enclosures at that point and the shutting down of B0E0 will not be breaking a RAID set.