A couple of weeks ago StorMagic announced their newest SvSAN 6 release. The basics are still the same: SvSAN takes the internal disks from two hypervisor servers (HyperV or VMware) and turns them into highly available shared storage. Yes, that’s a two server minimum, not three; so this should be a little bit cheaper compared to VMware VSAN and the likes. What’s new in version 6 is the addition of an Advanced edition with SSD and memory-based caching and tiering.
write cache
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MCx FAST Cache is an addition to the regular DRAM cache in a VNX. DRAM cache is very fast but also (relatively) expensive so an array will have a limited amount of it. Spinning disks are large in capacity and relatively cheap but slow. To bridge the performance gap there are the solid-state drives; both performance wise and cost wise somewhere between DRAM and spinning disks. There’s one problem though: a LUN usually isn’t 100% active all of the time. This means that placing a LUN on SSDs might not drive your SSDs hard enough to get the most from your investment. If only there was software that makes sure only the hottest data is placed on those SSDs and that will quickly adjust this data placement depending on the changing workload, you’d have a lot more bang for your buck. Enter MCx FAST Cache: now with an improved software stack with less overhead which results in better write performance.
When troubleshooting performance in a CLARiiON or VNX storage array you’ll often see graphs that resemble something like this: write cache maxing out to 100% on one or even two storage processors. Once this occurs the array starts a process called forced flushing to flush writes to disk and create new space in the cache for incoming writes. This absolutely wrecks the performance of all applications using the array. With the MCx cache improvements made in the VNX2 series there should be a lot less forced flushes and a much improved performance.
In September 2013 EMC announced the new generation VNX with MCx technology (or VNX2). The main advantage of the new generation is a massive performance increase: with MCx technology the VNX2 can effectively use all the CPU cores available in the storage processors. Apart from a vast performance increase there’s also a boatload of new features: deduplication, active-active LUNs, smaller (256MB) chunks for FAST VP, persistent hotspares, etc. Read more about that in my previous post.
It took a while before I could get my hands on an actual VNX2 in the field. So when we needed two new VNX2 systems for a project, guess which resources I claimed to install them. Me, myself and I! Only to have a small heart attack upon unboxing the first VNX5400: someone stole my standby power supplies (SPS)!
A new quarter, a new VNX Uptime Bulletin! This month is all about target releases of code and associated bugs. It’s important to keep up to date with current code releases; not only because certain newer models of disks/modules may not be supported by old code, but also because EMC is constantly fixing known problems and bugs. This VNX Uptime Bulletin headlines with VNX OE 33 updates and continues with target code for R32 and R31.