Exchange single-instance storage

This concept is not new in Exchange 2003 and actualy has been around since Exchange 5.5. It is a faily powerfull feature is you bare in mind that a lot of emails these days carry large attachments.

Microsoft Exchange Server 5.5, Microsoft Exchange 2000 Server, and Microsoft Exchange Server 2003 maintain single-instance storage of messages. If a message is sent to one recipient and it is copied to 20 other recipients who reside in the same mailbox store, Exchange maintains only one copy of the message in its database. Pointers are then created. These pointers link both the original recipient and the 20 additional recipients to the original message. If the original recipient and the 20 additional recipients are moved to another mailbox store, only one copy of the message is maintained in the new mailbox store.


Update 5-12-2005 : the missing link : http://support.microsoft.com/default.aspx?scid=kb;en-us;175481

Peter de Haas
Peter de Haas

Peter is gedreven door de grenzeloze mogelijkheden van technologische vooruitgang. Met meer dan 35 jaar ervaring in de IT heeft hij talloze ontwikkelingen zien opkomen en hun impact op organisaties en mensen meegemaakt. Met een scherp oog voor het identificeren van oplossingen waar anderen alleen problemen zien, is hij een ware expert in digitale transformaties.
Peter helpt individuen, teams en organisaties bij het ontwikkelen van nieuwe vaardigheden en het implementeren van baanbrekende oplossingen die werk beter maken. Zijn inzichten en ervaringen maken hem een gewaardeerde bron voor iedereen die de nieuwste technologische trends wil begrijpen en toepassen.

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17 reacties

  1. It wasnt new in Exchange v5.0 either. It was new in cc:mail back in 1990 or thereabouts.
    However, the days of the shared object store are over. Exchange’s continued unreliablilty (mind you -it *is* still based on “Jet” [Access, for us old hacks]) means that MS really have to get it onto ANY other database product – such as SQL.
    Hang on, didnt Kodiak promise this a few years ago ? Oh. That was dropped. Will it be in E12 ? Ah… No…
    Shame. Did you go tell the Exchange team that they are losing Microsoft Business ?
    And were you invited to the Exchange 5.5 “Wake” in London ? It was hosted by Microsoft… Another way of saying “screw you” to all those folks on Exchange 5.5, I guess.
    All those folks on the UK “Exchange unplugged” tour…
    Ouch.
    –* Bill

  2. Bill,
    Not sure if Microsoft is losing (Exchange) business. Actually marketshare of Exchange is growing at the expense of Notes and Groupwise, so that’s not it.
    How does Notes handle attachments; is this also single instance or actually duplicated per user ?

  3. Hi Peter
    It can be either single store or duplicated (or even a hybrid of both) in Notes. Personally, I go for duplicated store mail method as it makes corruption recovery really easy to get over.
    For example, the Domino server crashes and 3 mail files become corrupted…. worst case scenario is that I have to restore those three mail files, and all other users are unaffected.
    MSEX though – server crash and single store becomes corrupt… worst case scenario is that everyone is out until restore is complete…
    Disks are cheap – downtime isnt.

  4. It works just fine on ND6 guys… And I have seen the affects of it getting corrupted on Exchange aswell…
    It is not a selling point on any product…. It is a feature and many would say a limitation to any product. Domino gives you the luxury of choice…

  5. Sounds a bit sour Bill. Because in Domino no customer could deploy single store reliable (if it got corrupted and it did! it took forever to repair before it got up) it now isn’t a great feature for exchange?

  6. @ Paul,
    I did not bring it up as a key selling point for Echange. Merely a feature that has its benefits in some situation more than others
    “Disks are cheap, downtime isn’t”. You have a point there, however, I do see a lot of organisation getting worried about the big amount of storage they require and the facilities required to maintain their uptime such as failover / bbackup and restore. The amount of storage required also works through in these aspects and soon you are talking big money; beyond just the cheap disks.
    And what about compliance / the need/requirement to archive email; also here it starts with cheap disks and soon goes beyond the hardware cost.

  7. Peter-
    It’s funny you should bring up backups/restores as, in my mind, this is the achilles heel of the single copy object store (SCOS), regardless of which mail platform you are running. I have been a user of cc:Mail, Exchange, Groupwise, and Notes at a number of different Fortune 500 companies over the last 11 years. I know what it’s like to have a cc:Mail Post Office completely destroyed and to have an entire Exchange server taken off-line because some big wig needed a restore done right now. Even with no data loss due to transaction logging, the number of man hours lost waiting for the servers to become available again is agonizing for the users and completely frustrating for the IT team.
    I have also experienced the flexibility/costs that individual mail files can bring to the table. The mere fact that the size of one person’s mail file doesn’t significantly impact the performance of another person’s mail file is a key selling point for users. Also, with the addition of true active/active clustering to the mix, the ability to simply delete the mail file and replicate a new copy for the user without any loss of data or time is invaluable. In these days of $1000 terrabyte SAN solutions, the cost savings that SCOS might buy you on the disk space is easily lost the first time your server is down for 4 hours while the SCOS is being restored.
    But the real point of all this is that, with Exchange, you don’t have a choice on which one you are going to use. You will be using SCOS, whether you want to or not. With Domino, you can determine which architecture works best and even mix architectures on different servers or just for different sets of users. Give marketing folks, who like to send the same file back and forth without any changes, SCOS and let the executives have their own mail files for easy restores due to fat finger deletions.
    IMHO, the best place for SCOS is in mail archiving facilities where mail goes in, gets stored for long periods of time, and is rarely accessed. Almost all of the vendors in the Archiving arena tout this feature and their reasoning behind it is very sound.
    Sean—

  8. Hi Bill,
    I think you may have been misinformed about Exchange running on an Access database. I think whoever told you this may got their Jet Red and Jet Blue database engines confused.
    As for Exchange losing Microsoft Business – Microsoft is now the market leader according to most analysts. (IDC, Gartner etc) – and Growing.
    I’m sorry you misinterpreted the wake in London – it most certainly was not intended to say “screw you” as you politely put it.
    I believe that Exchange 5.5 was released before Notes 5 and we’re still supporting it now. And I’m pretty sure Notes 5 support ended a couple of months ago.
    Are you implying that IBM said something similar to their customers ? I know they didn’t. It’s just a fact of life that support has got to end at some time.
    As for the Unplugged tour – really enjoying it thank you for asking.

  9. @John: 1. Please tell us the details about Jet Blue/Jet Red and the relationship (if any) to Access. I really want to know.
    2. I think you will agree that there is a difference between having to extend support for a product that a large share of the customers are still using (Exchange 5.5) because of the major changes (AD for instance) needed to migrate (!) to another version and ending support for a version most of the customers aren’t using anymore because upgrading is so incredibly easy. You know: backwards compability, OS and hardware independent and stuff.

  10. @Jan,
    Jet Blue / Red, here’s your answer : http://www.microsoft.com/technet/prodtechnol/exchange/guides/E2k3TechRef/764d8347-a99b-408a-a774-f1263797c3b0.mspx
    On the left menu (after you clicked the link) is much more info on Exchnage and its datastore. Good to see you want to get educated 🙂
    I do agree with you that the upgrade from Exchnage 5.5. to newer versions is not the most straighforward excercise. I have some doubts opn Lotus Notes upgrades being very easy and straighforward either.
    Downward compatibility as you mention is not a often needed requitrement fo Exchange (mail / calendar only, but is for Lotus Notes, because of the applications. Diffrent solutions, different requirements ?

  11. You have doubts, Peter, of the very easy and straightforward nature of upgrading a Domino server? Over the past five years, I’ve upgraded more than a hundred serves from Domino 4.x to 5 and then from 5.x to 6.5. In general, I can shut down Domino, install the code, restart the box, and walk away from it in less than two hours.
    I’ve never lost functionality of my applications. I’ve never had to stop and rebuild an entire box. I’ve never lost mail. I’ve only once had an install flake out on me and have to start anew — and that was thanks to a power catastrophe.
    Otherwise, it really is that easy. I’m starting a new gig in the very near future. If you’d like to see in person how easy it is to upgrade a large organization’s Domino infrastructure, I’ll see what we can do to bring you into the datacenter.

  12. @Bill,
    My doubts are not addressed at Lotus Notes specificly, but in general. Migrations very often are not only an upgrade of OS or Applications but also include stuff like consolidation of infrastructure, rationalisation of applications, etc.
    When you look at one of the key of Lotus Notes 6.x / 7.x as well as Exchnage 2003, server consolidation / site consolidation is one of the key TCO drivers. This process as poart of the migration must have more implications then just a smooth upgrade and this certainly goes beyond the glossy brochure of any product 😉

  13. My – how this thread has grown since I last looked!
    I just thought it was the usual job of correcting Peters misplaced enthusiasm for everything MS and negativity and misinterpretation of everything non-MS..
    but no.
    Right. (rolls up sleeves) – lets get started:
    Exchange is Market leader. Thats a good statement.
    So Jet is not access derived ? So whats it derived from ? If it was SQL, then Kodiak would have been a breeze, right? But that didnt happen, did it ? Or is it Foxpro ? So whats a Jet Red and Jet Blue ? Which is more reliable ?
    (NSF on the other hand is very very fast and very very reliable. Or you could use the new DB2 object store in Domino 7. Or both. At the same time. Whatever floats your boat)
    Support for Exchange 5.5. Well, since it runs on NT and support on that disappeared too, then its pretty much a dead duck. Domino 5 of course, you can run on NT, win2k, win2k3, linux, solaris, AIX, OS/400, HPUX, OS/2 (also dead) and of course zOs. (I’m sure I’ve missed out one. Oh – yeah – Linux on XBox!)
    So whilst the Domino 5 itself might be out of support, the OS hasnt been chopped from under its feet.
    Domino 5 of course doesnt suffer from the catastrophic regular “unrecoverable database corruption” that Exchange does. Nor does Domino 5 actually spread viruses in the same way that Exchange 5.5. does. So comparing the two is a little disingenous, wouldnt you say ?
    Exchange is Pain. Pain if you stay on 5.5, pain if you upgraded to 2000 a while ago, pain if you want to upgrade from 5.5 to 2003. Hence the unplugged tour, right ? Trying to get the remaining significant users of Exchange 5.5 off that platform, onto something MS coloured. Else you wouldnt have the tour right ?
    Out of the percentage of Microsoft customers, how many of those are still running Exchange v5.5 – technically dead product now ? Are you counting those in the grand total ? Is it still the rumoured 50% that it was last year ? Or has it dropped below 35% ?
    Again – must be significant numbers for the tour, right ? Cant just be three senior MS techies visiting their mate up north, right ?
    Yet – I dont see IBM running round calling their customers dinosaurs, or having a wake for a product.. Odd. Different cultures, I guess.
    I guess my last word is back to Peters comment about SCOS somehow saving money. I can buy a terrabite of Raid 5 disk on a NAS for under seven hundred pounds sterling.
    Disk is cheap. Downtime is not. Ask the Microsoft GOLD partner consultants who lost their exchange 2003 server this year for over a WEEK. A WEEK’s downtime. Consultants. 50-200 people. no email for 5 days. Boy, was their “Exchange Unplugged”, eh ? How many terrabytes of disk could you buy for that cost ?
    Imagine how many clustered Domino servers you could co-locate in DR sites and run active/active clustering on, all with separate disk subsystems.
    (Oh – Exchange doesnt do active/active clustering either. And isnt too hot on clustering over slower WAN links. All stuff that was in Notes v4.5 – when Exchange v4.5 was still in Beta. 10 years ago. [Yes, the Exchange beta was called v4.5, but the release was called v5])
    And so Domino – hell – a gold plated server running on diamond encrusted hard disks – is cheaper than risking your business running Exchange on a single object store.
    Hope this clarifies the matter,
    —* Bill

  14. @Bill
    You’re a blowhard man… This is an ancient thread, but you shouldnt be left with last word. Guys like you need to do a LOT less talking and ranting and raving, and a LOT more reading and learning and objective analysis. Im not even going to get into a point by point breakdown of you exaggerated and biased rant. It’s just famebait.
    It’s funny you feel you perform some service “correcting Peter’s misguided enthusiasm for all things MS”, but you cant recognize that your version of “correction” is simply forcing your own narrow-minded and extreme viewpoint. So his enthusiasm for all things MS is “wrong”, but your enthusiasm for all things *not* MS (basically, your anti-MS fervor) is “right”.
    Technology debate is at its best when the ideologues stay home.

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