Intel RS2BL080 and SSD Cache, is the Premium Key (AXXRPFKSSD) required

[Wixner]

Hello everyone.
This is my very first post, but surely not my last.

I am in the process of planning my new storage solution and have a question regarding the Intel SSD Cache on the Intel RS2BL080 Raid Controller:
Is the SSD Premium Key (AXXRPFKSSD) required to use SSD drivers as cache or does it simply improve the performance of the SSD Cache?

Sincerely
Wixner

 

[Jeggs101]

I thought you did need the key to enable the feature? there are other solutions for SSD caching out there though.

 

[Wixner]

I have really no idea

No Intel Documentation I've found so far states the obvious but as it is built upon wellknown hardware I'd hope someone here had the answer...

 

[supermacro]

If you want the equivalent of LSI's Cachecade & Fastpath then you do need the key. I have the Intel RS2BL080 and LSI hardware key but it didn't work. If I remember correctly it didn't even take the 30 days software trial key so you do need an Intel version of Cachecade (AXXRPFKSSD) to use SSD as cache.

 

[Wixner]

If you want the equivalent of LSI's Cachecade & Fastpath then you do need the key. I have the Intel RS2BL080 and LSI hardware key but it didn't work. If I remember correctly it didn't even take the 30 days software trial key so you do need an Intel version of Cachecade (AXXRPFKSSD) to use SSD as cache.

Alright, Thanks a lot for that answer

This however raises another question in my mind: If I buy the key and configures a 2x 120GiB SSD as Raid0 (240GiB in total, as you would have guessed), would i see any increase in performance if the only data in my storage is a 4TiB iSCSI Virtual Harddrive?

 

[supermacro]

You will, in fact, see a huge differernce with Cachecade. It might be better with one 240GB SSD than 2x 120GB. The SSD caching does support RAID1 for redundancy but the cost of 2x 120 RAID 0 should be about the same as 1x 240GB. The main reason is because each SSD actually takes a port away from your controller (unless you use a SAS expander but this still requires an additional mounting) so a single SSD is what I'd prefer.

Also, watch out if you're using 512GB SSD for caching. I know LSI claims SSD support uo tp 512GB (with any combination) but I think you actually have to make the SSD less than 512GB if you don't want any trouble.

 

[mrkrad]

cachecade 1.0 requires read-ahead enabled. drives can be raid-0 or single , the idea being that the SSD's should always be faster than the array behind them. IE 1 slow 250 meg ssd will lag down 6 15K SAS drives in linear read, but perhaps random i/o will be far faster due to latency.

cachecade 1.0 can suffer a loss of the ssd and continue to operate normally.

cachecade 2.0 with read/write requires a raid'ed ssd setup - raid 10 or 1 - same rule applies but you are writing and reading so if think about that you want redundancy and speed to 512GB. If the cachecade drive(s) fails, the entire array fails. 1 SSD in 2.0 read/write mode is INSANE and would be too slow imo.

Two 512gb (480gb after OP) in raid-1 would be okay, but 4 x 256gb with a little OP would be best in raid-10.

IIRC you can connect up an MSA2312sa ($499 ebay) to 1 external and 4 x 256gb to internal and the external sas (4x3gbps) can benefit from the hot caching.

Now if you have 4 servers (in a cluster box?) that can do this - you can connect 4 machines with cachecade to the same san (different luns of course) and they can have a good ole time.

It's highly SMART to overprovision for caching on cachecade 2.0 read/write. That samsung 830/840 pro will retain its speed and life if you say knock it from 512gb to 256gb - If you use the entire 512gb you will wear it out in a year or so and disk iops will drop by 10x when under continual load.

Seriously - i'd pick a crucial m4 $299 512gb and run it at 50% before i'd pick an OCZ and run it without OP.


I wish they made a cluster server where you had two internal or 4 2.5" internal pay "Blade" and then a slot for a 4i/4e cachecade controller. Then plug those 4 servers in a single $499 MSA2312SA with 12 4TB SAS RE4 drives (SAS is key here). Build 4 separate luns for each cluster server so there is no cache coherency , and go to town. Maybe this would allow you to rock raid-5/6 with nearline RE4 SAS drives while not feeling the pain of the 7200rpm speed.

 

[badatSAS]

I've seen a specific direction to NOT use Crucial M4's with cachecade somewhere, will try to find the link