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Robert Clemens
Phosphor

R720 with H710P CacheCade Question

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Trying to redesign my server to maximize database performance. I've not used cachecade before and thought I'd give it a whirl in my server to see if it helps database performance. It's hard to get a good read on the H710P cachecade information and most information Dell puts out is pretty high level overview. I've read that cachecade 2.0 is not available on the H710P but the Dell posting talking about this was very old -- is this still true and only cachecade 1.1 is supported as a read-only cache?

I had a hard time pinning down up-to-date information on supported SSD drives for use with cachecade. I ended up buying a couple Samsung 850 PRO 128GB drives as I did read a few posts saying these worked well although the information was not directly from Dell. Since this is read-only cachecade I assume these ought to last long enough to make it worth it. Replacing these wouldn't be an issue if they wear. Not sure what kind of life to expect on these but presumably it would be decent enough. SLC would only be a reasonable option if MLC drives fail quickly.

The last unknown is how cachecade is applied to virtual devices. Is a cachecaid array global for the entire pool of virtual disks or do you have to associate it with a virtual disk? I specifically want to utilize this for my database server (Sybase ASE 15.7). Right now my Sybase guest is on an 8 disk 15K SAS 300GB RAID10 array. Performance is okay but I'd like to speed it up as the data is critical for accessibility within a reasonable access time. 

The good news is I have a test server that I get to test all of this on but not being familiar with cachecade and the best way to get performance I thought I'd ask.

Currently I have 2 arrays (no cachecade).

RAID5 DATASTORE1 = 8x 300GB 10K SAS drives in RAID5 for ESXi host and vmware guests.

RAID10 DATASTORE2 = 8x 300GB 15K SAS drives in RAID10 for Sybase ASE (RHEL6) guest.

Here is what I'm thinking about doing (any advice is appreciated):

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RE: R720 with H710P CacheCade Question

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Hello

I've read that cachecade 2.0 is not available on the H710P but the Dell posting talking about this was very old -- is this still true and only cachecade 1.1 is supported as a read-only cache?

Yes, cachecade 2.0 was never released on our PERCs. We dropped cachecade completely and moved to Sandisk DAS Cache on later generations. You can read more about it here:

http://www.dell.com/learn/us/en/04/server-technology-components-caching

The last unknown is how cachecade is applied to virtual devices. Is a cachecaid array global for the entire pool of virtual disks or do you have to associate it with a virtual disk?

It is global. There are very few options available when configuring cachecade. You can create, delete, or name a cachecade virtual disk. The rest of your questions should be answered in this article:

<ADMIN NOTE: Broken link has been removed from this post by Dell>

There are two things of note in that article:

  1. It states multiple times that ONLY the 1GB version of the H700 supports cachecade. That statement is true, but the feature was included with the 512MB version of the H700 by mistake. To my knowledge we have not removed the cachecade feature from the 512MB version, but the feature is not supported on that card and it may not be available in all firmware versions of that card.
  2. It states in that article that ONLY SSDs with Dell identifiers are supported. I do not know if we explicitly block non-Dell drives in cachecade arrays. If you decide to use 3rd party drives then I would recommend you make sure you can use them elsewhere or return them if they do not function properly. If you use 3rd party drives that another site says will work then keep in mind that any firmware change to the controller or drives may cause communication problems. We optimize our controller and HDD firmware for our PERCs and HDDs. We do not design the firmware for broad compatibility with other products.

Thanks

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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Robert Clemens
Phosphor

RE: R720 with H710P CacheCade Question

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Thanks for the info. I'll give it a whirl and see if it helps. Worst case scenario is I use the SSD's in workstations and I'm out nothing but the effort. 

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