It has been a while since my last post, i’ve been busy on a lot of fronts, i’ve been revising for my VCP4 Exam (which i passed ), working heavily on projects at work and also had a holiday.
After my hectic month i’ve now had the chance to catch up with the latest Exchange 2010 product changes and felt compelled to post on what I discovered within this. It appears that Microsoft has removed from 2010 Single Instance Storage functionality/
Single Instance Storage
Introduced in Exchange 4.0, SIS (or Deduplication) ensures that attachment files that get emailed to multiple people are basically only stored as a single master file to avoid storing multiple copies of that file within every user mailbox, so from an overall Exchange Database perspective multiple sent files appears on used storage as just the size of a single file.
You were probably as dumbstruck as I was when I read about EOL of SIS on the lastest Microsoft blurb, and your probably thinking to yourself exactly what I did which was there must be a new type of SIS or a new fandangled name for SIS that either improves upon SIS or even completely new architecture to save on storage consumption all together. Well it appears it was neither of those…I digged deeper and came up with the following blog post to that it is now completely EOL.
It does seem that like me readers of the official Microsoft blog have great concerns on the architectural changes and the side effects within a typical large scale environment of implementing 2007 compared to 2010. Additionally echoed are concerns on what types of problems it will lead to in future within an operational environment day to day. To be frank Microsoft sound a bit blase when providing justification on why they have removed SIS, they seem to infer that technology like SIS is legacy and customers do not actually benefit from storage reductions, and in fact SIS is being removed to provide performance benefit.
How Microsoft can measure that SIS is not usual anymore is beyond me, Exchange customer use cases are all different, but in reality in the field the actual fact regardless of what Microsoft think SIS however small has benefits to reduce storage costs for most organisations, additionally it has made things in Exchange more efficient in other areas such as reducing backup windows and the associated restore times for Exchange databases.
The justification from MS seems to be that today compared to 4-5 years ago Disk is cheaper and bigger and yes they are right, it maybe cheaper when they go and compare this to DAS connected environments I have no issues with this. However my issue is that most large organisations like mine do not use DAS for large scale Exchange and large enterprises don’t do this with Exchange due to some of the following reasons;
- DAS does not provide Volume snapshot capability for backup and restoration activity
- DAS Storage volumes cannot be replicated for any purpose to a secondary offsite or local array
- Backup windows with DAS compared to using a SAN are not even worth providing examples of the difference, backup across the wire with DAS is unquestionably for large volumes of Exchange data going to be slower
- You cannot clone a DAS storage volume nondisruptively in the background and quickly like you can on SAN, this is usefull for things that you should regulary perform such as Production backup integrity test.
- You have dependancy with DAS between host and storage, you can move/change a Fibre connected server much easier than DAS.
- Try providing cache priority or QoS to a DAS volume!
- Try managing DAS remotely and from central consoles!
- On a TCO front a SAN most probably provides you with much better cost savings and operational savings compared to having pockets of large storage pool with DAS
I’m not a SAN Bigot (maybe just a bit) but I’m sure some of the above reasons orgs use SAN shows what limitations arise by using DAS in the enterprise and why for applications like Exchange you need to implement such infrastructure.
The example cost hike
So to see what type of cost increase I may experience with no SIS by Upgrading to Exchange 2010 take the example calculation based on 1000 Users being sent a Mail with the Christmas message from the CIO which happens to be a 5MB attachment, this attachment being sent to 1000 people would calculate to theoretically 5GB of storage consumption on the Exchange DB which would be avoided with SIS in Exchange 2007, multiply that example in a typical messaging environment with Carbon Copy of example large presentations, more company announcements with attachments (maybe a Lotus Notes Quotation from Procurement?) etc and it will certainly start to become a very expensive option to use Fibre Channel with something like SIS.
Additionally lets not forget here that most organisations who have deployed 2007 have most likely implemented this on new SAN Arrays which are not likely to be renewed and have the capability to host 2010, a SAN is not unfortunately something you can throw away and replace with DAS, Additionally remember DAS has the hidden costs associated with operational management.
So to summarise on the negative side of this post I am not happy with such functionality being removed, by removing SIS from technology I will have no choice to upgrade to in future i’ve just increased my storage costs by 10% and also increased the volume of disk that I now require in my array moving forward (tough using proprietory tech hey). Lastly to put this into perspective I can’t be bothered to find pricing from Microsoft on Exchange but I am more than sure the price of the software is now not 10% less with 2010
The positive comments for Microsoft from this post
I’m not that hard on Vendors all the time, i’ve got some positive comments here. My positive side of this post mainly focuses generally with the fact features such as SIS moving forward means you should be focusing more on treating your storage strategy and all round planning more seriously with complete Archive methodology.
With a Commercially available Archive solution such as Symantec E-Vault or Quest Archive manager means you can host mail items on lower tier SATA or archive disk storage media, which in turn means you reduce the size of primary Exchange storage and the associated storage requirements of the higher tier level of storage. Importantly however by archiving shouldnt mean you cut your own nose off despite your face and replace SAN with DAS, it still has the tangible benefits across most large enterprise environments for many other reasons.
Maybe i’m being unfair here to Microsoft with my vendor rants, we have had SIS functionality reducing storage costs for a while wihtout realising and have taken it for granted, I think more and more moving forward we will need to shift to more focus on alternate strategy using Archiving products more and more and be sensible about the lifecycle of storage management within email environments. Longer term it will be interesting to see results from people migrating to 2010 to see if they notice a dent in storage costs if they are using SAN and not the horrible dreaded DAS!