Ask the Expert: Block Deduplication and FAST Suite Tiering in the New VNX

dynamox wrote: very few changes to Navi Analyzer, that tool has not changed  in more than a decade. Look at performance tools that have been developed for VMAX (SPA and now Unisphere for VMAX). So many metrics, very nice export options (UPV/BTP). Analyzer is so 1990's (thank god you include it now in base package). VNX Monitoring and Reporting has a long way to go. Why so little focus on developing a more robust performance analysis tool ?

Yes,  the vnx lacks pretty bad in the performance monitoring side of things...

ayas wrote: Hi there .. We hear a lot about BLOCK deduplication in NG VNX , but what about File level ? I would like to know about File deduplication as well. Can I apply deduplication against LUNs assign to DMs ? If it is not good .. or not supported ... When will this be supported ? Other vendor products are tend to have Block level deduplication , It would be nice to cover NAS area by EMC ! thanks !

Block Deduplication is not reccomended for use with File Storage. As the LUNs become Thin LUNs when Block Deduplication is enabled, this recommendation goes hand in hand with the recommendation of not using Thin LUNs with File.

The File side has an existing Deduplication and Compression feature that has been around for a number of releases. Single Instance Storage is the Deduplication technique on the File side. This means if the contents of a file are exactly the same, the file is single instanced and all references of that file will point to the one copy the software keeps on the system.

阿超_SteveZhou wrote: sorry, i don't really understand the word "spreads out" here, what would the original FAST VP statistics gathering & analysis processes work? Each pool has its own set of processes, or just threads?

Each Pool does its own statistics gathering and analysis. This data is then used during the relocation window to decide which slices need to be moved.

By "spreads out" I mean that the processes for each pool run at different times. They will be spaced out as to not run all at once.

SjurAndre wrote: Hey RyanP RyanP wrote: Multicore Cache and Multicore FAST Cache are Block Deduplication aware, which means only single copies of data from a pool can end up in Multicore Cache or Multicore FAST Cache. If 5 LUNs all had the same 8 KB block in Multicore Cache and Multicore FAST Cache, when these 8KB blocks are deduplicated, only a single instance of each will be left in each cache. With this said, Multicore Cache still promotes data in 64 KB blocks. Will there be any background processes that handles the lefoverspace when the blocks get deduped? Like any kind of reorganisation of the blocks? So they dont get fragmented.

The "freed" 8 KB areas due to deduplication will be reused by new 8 KB data coming into the array. This will help fill in gaps left by deduplication. As I mentioned in another post, when the Thin software recognizes a slice is minimally being used and there is enough space on another slice for the data, the clean-up process is called and the slice contents will be moved to the other slice, and the 256 MB slice will be freed.

hi RyanP

thanks for the update ,,

Now I understand why NG VNX call deduplication ``Block `` it is now clear !

thanks

Aya

Hi,

The VNX MCx is post processing de-duplication and not in-line. What were the design factors which over-rode one over the other? Was the amount of memory a factor or not being able to isolate an area for dedupe? say like the Symmetrix Dynamic cache partitioning.

I take it the impact to I/O being served to clients is not impacted by the deduplication as it is run on a scheduled basis?

This will come up in conversation from Customers etc so would be nice to have a bit more info on minimising the impact of post-process dedupe or in-line draw backs.

Thanks,

Victor

p.s. Great ATE discussion

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Good stuff.

there was actually a lecture on this topic during EMC World. I hope you attended!

Tim - did you get to go to Vegas and not tell us?

glen