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Present LUN from VPLEX and VMAX to ESX cluster simultaneously?
Hello everyone,
I asked a similar question in VMWare communities, but have not received any replies.
We currently have several ESX clusters sitting on a VMAX array behind VPLEX. We want to keep the clusters on VMAX, but move them out from behind the VPLEX array (direct attach them to VMAX).
Can you leave the VPLEX LUNs connected, and simultaneously attach the same LUNs to the cluster from the VMAX? Then, we would stop presenting the LUNs from VPLEX, and operate solely from the direct attached VMAX.
The concern is that the disk NAA is virtualized on the VPLEX, and this would mean that the ESX cluster would see the same disk with two different NAA numbers at the same time.
Does any one have any experience with this situation, or know if this process would work?
Thanks,
Tanner
lun1
12 Posts
0
May 27th, 2016 00:00
I think this is a bad idea for many reasons, but most importantly is the fact that the VPLEX has its own read cache, so if a volume is written to outside of VPLEX (directly to VMAX) the cache will contain invalid data for those blocks, as the VPLEX would not know they had been updated since the last time they were read from disk, and you could get data corruption.
If you have downtime and just switch things over, it should work as long as you didn't do any advanced provisioning on the VPLEX (anything except 1:1 mapping of the volume)
//bd
TannerR
15 Posts
0
May 27th, 2016 11:00
Hi lun1,
Thank you for your feedback. We were going to test the process on a test cluster, but you made very valid points. We have decided to just provision new direct attached VMAX LUNs and vMotion as necessary. As with most shops, we cant take a chance that something gets messed up and we loose data.
edit: As you suggested, if we could take downtime, we could just switch things over and be done. Unfortunately, however, we cannot take outages on our production clusters, so we will be forced to provision new LUNs.
Thanks,
Tanner