3PAR OS 3.3.1 Performance Enhancements

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There are a bunch of performance and under the hood enhancements in 3PAR OS 3.3.1 which I wanted to take a deeper look at today, I have covered an overview of all the new features in a previous post.  Some of them are brand new features others are enhancements of old ones. Let’s look at each one in turn

Adaptive flash cache (AFC) – allows SSD’s to be used as an extension to the controllers onboard DRAM memory to accelerate reads.  Analysis of the 3PAR install base has demonstrated that there is regularly capacity free in the AFC and to maximise its benefit the cache should be as full as possible. In 3PAR OS 3.3.1 AFC remains for reads only but extends the type of requests allowed further to include: large sequential I/O >64K and data read from snapshots.  Having more data in cache will of course increase the chances of a hit, these new types of request take a back seat to those previously defined in AFC i.e. if AFC is full with small reads it will not flush these out to allow a large sequential read.

Express Writes – Express writes aims to deliver lower latency by delivering lower CPU interrupts per IO.  This is achieved by sending the data along with the command rather than waiting for the target to request it. Previously this was only available with FC protocol, this is now extended to iSCSI for the 8000 and 20,000 systems. This will be enabled automatically at upgrade and can result in up to 40% improvements in latency for iSCSI writes

Multi Queue – Is another option that will automatically be turned on and self-optimised in 3Par OS 3.3.1. Previously each SAS or FC port was locked to a processor core, this worked well if all ports were utilised but left cores idle if all ports were not fully utilised.  Multi-queue cores can be shared between ports allowing for greater utilisation

Persistent Checksum – Ensures the integrity of data by performing a checksum on the data from the HBA to the disk.  The current implementation of Persistent Checksum is proprietary, hence the requirements for specific HBAs.  The new implementation switches to using standard T10 diff which is reliant on the host OS not the HBA’s and therefore widens the support.

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3PAR Dedupe + Compression Deep Dive

3PAR Mega News Bundle – Including Compression


3Par Gets Flashier

For a while standard 3Par owner’s could be forgiven for looking on with envy to those lucky enough to own the all flash 7450 model, with its all flash massive IOPs crunching potential and new features such as dedupe. Well feel jealous no more 3Par fans, last week HP shared out the flashy goodness to the hybrid arrays by announcing a bunch of features that will well and truly pimp out your 3Par, to an extent which would even impress Xzibit. Check out this orange Roller below, I bet Rolls Royce didn’t see that coming when it rolled off the production line.



3 Par OS 3.2.1

The announcements from HP centred around using flash to deliver an extra whack of performance for your 3Par. The key new features were in summary Adaptive Flash Cache, Dedupe and Express Writes. All these new features are enabled by upgrading to 3Par OS 3.2.1, and the even better news is that all these new features are freebies i.e. they are included as part of the standard 3Par OS. Let’s break each one of these elements down and see how it is going to deliver additional performance.

Adaptive Flash Cache

Adaptive flash cache is about utilising SSD’s to expand the size of the cache. A bigger cache allows more data to be stored in cache and hence a greater likelihood of being able to retrive data from cache. This is great news for anyone’s environment that has high random reads, judging by the fact my most popular post of all time is still Adaptive Flash Cache Deep Dive lots of other people agree. Do check out the deep dive it’s got lots of good info in it. Also check out this Adaptive Flash Cache video Calvin Zito has put together where he shows a practical demo of the kind of performance improvement that is possible.

Express Writes

Next up Express Writes, again like Adaptive Flash Cache this new feature is aimed at improving latency but for writes by optimising the FC protocol. Express writes aims to deliver lower latency by delivering lower CPU interrupts per IO, Performance improvements can be up to 10%.


Dedupe was announced earlier this year for the 7450, and last week’s announcements was that it will now be available to all 3Par systems with the Gen 4 asic i.e. the 7000 and 10,000. The way the dedupe works is exactly the same as on the 7450, inline and by the assigning a hash to each unique incoming write and then comparing the signature of further incoming writes to ensure they are unique. The dedupe process is demonstrated in the diagram below taken from the HP whitepaper HP 3PAR StoreServ Storage: optimized for flash. The limitations to using dedupe are that it is only available on the SSD tier and the technology cannot be combined with AO.

Final Thoughts

This new set of features has to be one of the most compelling reasons to upgrade in some time. I’ll be upgrading ASAP and really making those SSD’s work for their living!

You can see a summary of the announcements in this ChalkTalk.