AX100i Write Cache Issue 1

[lhuegele]

We have an EMC AX100i iSCSI san from Dell that came with a 1U ups. We moved this SAN into our new datacenter that has a huge UPS for the entire center. There was a serial cable connecting the SAN to the 1U ups so that the SAN could talk to the UPS.

Since we have UPS to each rack in the new datacenter, we didn't want to move this 1U ups as well, so we moved the SAN without it's little ups partner. However, apparently the AX100i requires this to be present in order for the write-cache to be enabled.

Does anyone know if there is a way to turn the write-cache back on without having to move and hook up the 1U ups to it? We called Dell and they said it was impossible, but I just find that hard to believe.

Thanks!

 

[sanster]

The purpose of this cable is to tell the controller if there has been a power outage and to flush it's cache before cleanly powering itself off. Even the higher end arrays do this to protect the data. I don't know if you can turn that feature off, but I wouldn't suggest it anyway as it would put the data at risk. Which for most companies these days, is the most valuable asset.

 

[lhuegele]

Hi Sanster. I appreciate the response. I understand the need for a UPS and why you don't want a write cache if you don't have backup power.

What I don't understand is why you don't at least have some way to tell the storage array "hey you have backup power, so turn write cache back on" manually. We moved into a new data center (our switching closets were our datacenters before) that has dual redundant UPS to each rack so it seems silly to me that we had to move a little 1U ups into that rack with the storage array just so the storage array can decide for itself if it has backup power.

We confirmed with Dell that there is no way to manually turn write cache back on - the storage array MUST confirm for itself (via the serial cable) if it has backup power.

Thanks,