Not all data is accessed equally. Some data is more popular than other data that may only be accessed infrequently. With the introduction of FAST VP in the CX4 & VNX series it is possible to create a single storage pool that has multiple different types of drives. The system chops your LUNs into slices and each slice is assigned a temperature based on the activity of that slice. Heavy accessed slices are hot, infrequently accessed slices are cold. FAST VP then moves the hottest slices to the fastest tier. Once that tier is full the remaining hot slices go to the second fastest tier, etc… This does absolute wonders to your TCO: your cold data is now stored on cheap NL-SAS disks instead of expensive SSDs and your end-users won’t know a thing. There’s one scenario which will get you in trouble though and that’s infrequent, heavy use of formerly cold data…
data placement
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XtremIO is the new all-flash array from EMC, announced not too long ago. Flash has an enormous performance advantage over traditional spinning disks. Although there are no moving parts in a solid state drive, they can still fail! Data on the XtremIO X-Brick will still need to be protected against one or multiple drive failures. In traditional arrays (or servers) this is done using RAID (Redundant Array of Independent Disks). We could simply use RAID in the XtremIO array, but SSDs behave fundamentally different compared to spinning disks. So while we’re at it, why not reinvent our approach of protecting data? This is where XtremIO XDP comes in.
The storage market has gradually been using more and more flash to increase speed and lower cost for high I/O workloads. Think FAST VP or FAST Cache in a VNX or SSDs in an Isilon for metadata acceleration. A little bit of flash comes a long way. But as soon as you need enormous amounts of flash, you start running into problems. The “traditional” systems were designed in an era where flash wasn’t around or extremely expensive and thus simply weren’t designed to cope with the huge throughput that flash can deliver. As a result, if you add too much flash to a system, components that previously (with mechanical disks) never were a bottleneck now start to clog up your system. To accommodate for this increased usage of flash drives the VNX system was recently redesigned and is now using MCx to remove the CPU bottleneck. But what if you need even more performance at low latency? Enter EMC XtremIO, officially GA as of November 14th 2013!
The last breakout session I attended at EMC World 2013 was titled “Leveraging SSD: Designing for FAST Cache & FAST VP on Unified Storage”. By far one of the best breakout sessions of the week for me: technical and I can apply it in the field on pretty much a daily basis!
If you’ve got SSD drives in a VNX you can use it in two ways: as FAST Cache or as an extreme performance tier in your storage pools (FAST VP). Either of these implementations has advantages and disadvantages and they can also be used concurrently (i.e. use FAST Cache AND FAST VP). It depends on what you want to do…
But let’s start at the beginning: first you need to figure out your skew! What?!