In Part 4 of this 2-part series on VNX7500 configuration guidelines I’m going to simply paraphrase Loyal Reader Dave’s comments on my previous posts, because he raised a number of points that I’d forgotten, and the other two of you reading this may not have read the comments section.

While I was heavily focussed on a VNX7500 filled with 600GB 10K SAS disks, it is important to note that with the VNX you can *finally* mix any drive type in any DAE. So if you have workloads that don’t necessarily conform to the 15 or 25-disk DAE this is no longer a problem. That’s right, with VNX it does not matter – SAS,EFD, or NL-SAS can all be in the same DAE. Whether you really want this will again depend on the workload you’re designing for. And before the other vendors jump in and say “we’ve had that for years”, I know you have. Dave also mentioned that the ability to mix RAID types within a heterogeneous FAST VP would be handy, and I agree there. I’m pretty sure that’s on a roadmap, but I’ve no idea when it’s slated for.

It is also important to expand a FAST-VP pool by the same amount of disks each time. So if you’ve got a 15-disk pool to start with, you should be expanding a pool with another 15 disks. This can get unwieldy if you have a 60-disk pool and then only need 5 more disks. I’m hearing rumours that the re-striping feature is coming, but so’s Christmas.

While you can have up to 10 DAE’s (15 disk DAE) on a bus or a maximum of 250 disks (new 25 disk DAE), Dave still follows legacy design best practices with the CX5s: RAID1/0 across two buses, and FAST cache across all available buses. I agree with this, and I don’t think the VNX is quite there in terms of just throwing disks anywhere and letting FAST-VP take care of it. Dave suggested that I should also mention that the cache numbers and page cache water marks should be adjusted to the best practices (this has changed for VNX models). I’m hoping to do a post on this in the near future.

While the initial release of Block OE doesn’t allow connectivity to another domain, the latest Block OE 05.31.000.5.502 has just gone GA, and I think this has been fixed.

If I get some time this week I’ll put up a copy of the disk layout I proposed for this design, including the multiple variations that were used to try and make everything fit nicely. Thanks again to Dave for his insightful commentary, and for reminding me of the things I should have already covered.