Restoring an Exchange 2007 mailbox using EqualLogic’s ASM/ME

 

 

Ask most IT Administrators in small to medium sized organizations to recover an Exchange mailbox, and you’ll get responses like, “how important is it to recover it?”  and “How much of it is gone?”  You might even get the slightly patronizing “Oh, well you were close to your storage quota anyway”   This is IT-speak for “I don’t want to recover it” (labor intensive), “I’m not sure if I can recover it” (it didn’t work the last time they tried), or “I can’t recover it, and don’t really want to tell you that.”  Trust me, I’ve been there.

The recovery process has ranged anywhere from non-existent (Exchange 4.0) to  supposedly easy (according to the glossy ad of the 3rd party solution you might have purchased, but could never get to work correctly), to cautiously doable, but an incomplete solution, with later versions of Exchange.  As each year passes, I’m always hoping that technology can make the process easier, without pushing through another big purchase.

I got my wish.  Technology has indeed improved the process.  I recently had a user mailbox’s contents vanish.  Who knows what happened, but I had to get the mailbox back fast, so I had to familiarize myself with the process again.  This time, since my Exchange 2007 Server is virtualized, and the Exchange databases and logs reside on guest attached volumes, I was able to take advantage of EqualLogic’s “AutoSnapshot Manager Microsoft Edition” or ASM/ME. 

ASM/ME allowed me to easily recover an Exchange Storage Group, then mount it as a Recovery Storage Group (RSG).  From that point I could restore just that single mailbox on top of the existing mailbox.  What a refreshing discovery to see how simple the process has become.  And that, it just worked.  No weird errors to investigate, no tapes to fiddle with.  It was a complete solution for a mailbox recovery scenario.  The best part of all, was that its a function available free of charge to any EqualLogic user who is using the Host Integration Toolkit (HITKit) on their Exchange server. 

Here is how you do it.

1.  On the Exchange Server, open up ASM/ME, highlight the smart copy collection that you’d like to recover.  I say “Collection” because I want to recover the volume that has the DB on it and the volume that has the Transaction Logs on it at the same time.

2.  Select option to “Create Recover Storage Group”

3.  Select the desired Storage Group

4.  It will prompt for two drive letters not being used.  This will represent the location of the restored volumes.  So if the Exchange databases are on E: and the Transaction Logs are on F:, it might prompt you to used “G:” and “H:” respectively.

5.  It will complete with the following message
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6.  Close out of ASM/ME, and launch the “Database Recovery Management” in the Toolbox section of the Exchange Management Console.  This leads to the “Exchange Troubleshooting Assistant in the Exchange Management Console (EMC).

7.  Run through the restoration process.  It will restore the selected mailbox on top of the existing mailbox.

8.  Once it is complete, as the dialog above instructs, you will need to dismount and logoff the smart copy collection set with ASM/ME after the RSG is removed.

The process was fast, and worked the very first time without error.  I’d still prefer to never have to recover a mailbox, but it is nice to know that now, thanks to ASM/ME and the Exchange Database Recovery Management tool, that its really easy to do.

 

Helpful Links

A more detailed guide on using RSGs in Exchange:
http://www.msexchange.org/tutorials/Working-Recovery-Storage-Groups-Exchange-2007.html 

Working with a Recovery Storage group in the Exchange Management Shell (EMS) instead of the EMC.
http://technet.microsoft.com/en-us/library/bb125197(EXCHG.80).aspx

Replication with an EqualLogic SAN; Part 4

 

If you had asked me 6+ weeks ago how far along my replication project would be on this date, I would have thought I’d be basking in the glory of success, and admiring my accomplishments.

…I should have known better.

Nothing like several IT emergencies unrelated to this project to turn one’s itinerary into garbage.  A failed server (an old physical storage server that I don’t have room on my SAN for), a tape backup autoloader that tanked, some Exchange Server and Domain Controller problems, and a host of other odd things that I don’t even want to think about.  It’s overlooked how much work it takes to keep an IT infrastructure from not losing any ground from the day before.  At times, it can make you wonder how any progress is made on anything.

Enough complaining for now.  Lets get back to it.  

 

Replication Frequency

For my testing, all of my replication is set to occur just once a day.  This is to keep it simple, and to help me understand what needs to be adjusted when my offsite replication is finally turned up at the remote site.

I’m not overly anxious to turn up the frequency even if the situation allows.  Some pretty strong opinions exist on how best to configure the frequency of the replicas.  Do a little bit with a high frequency, or a lot with a low frequency.  What I do know is this.  It is a terrible feeling to lose data, and one of the more overlooked ways to lose data is for bad data to overwrite your good data on the backups before you catch it in time to stop it.  Tapes, disk, simple file cloning, or fancy replication; the principal is the same, and so is the result.   Since the big variable is retention period, I want to see how much room I have to play with before I decide on frequency.  My purpose of offsite replication is disaster recovery.  …not to make a disaster bigger.

 

Replication Sizes

The million dollar question has always been how much changed data, as perceived from the SAN will occur for a given period of time, on typical production servers.  It is nearly impossible to know this until one is actually able to run real replication tests.  I certainly had no idea.  This would be a great feature for Dell/EqualLogic to add to their solution suite.  Have a way for a storage group to run in a simulated replication where it simply collects statistics that would accurately reflect the amount of data that would be replicate during the test period.  What a great feature for those looking into SAN to SAN replication.

Below are my replication statistics for a 30 day period, where the replicas were created once per day, after the initial seed replica was created.

Average data per day per VM

  • 2 GB for general servers (service based)
  • 3 GB for servers with guest iSCSI attached volumes.
  • 5.2 GB for code compiling machines

Average data per day for guest iSCSI attached data volumes

  • 11.2 GB for Exchange DB and Transaction logs (for a 50GB database)
  • 200 MB for a SQL Server DB and Transaction logs
  • 2 GB for SharePoint DB and Transaction logs

The replica sizes for the VM’s were surprisingly consistent.  Our code compiling machines had larger replica sizes, as they write some data temporarily to the VM’s during their build processes.

The guest iSCSI attached data volumes naturally varied more from day-to-day activities.  Weekdays had larger amounts of replicated data than weekends.  This was expected.

Some servers, and how they generate data may stick out like sore thumbs.  For instance, our source code control server uses a crude (but important) way of an application layer backup.  The result is that for 75 GB worth of repositories, it would generate 100+ GB of changed data that it would want to replicate.  If the backup mechanism (which is a glorified file copy and package dump) is turned off, the amount of changed data is down to a very reasonable 200 MB per day.  This is a good example of how we will have to change our practices to accommodate replication.

 

Decreasing the amount of replicated data

Up to this point, the only step to reduce the amount of data replication is the adjustment made in vCenter to move the VM’s swap files off onto another VMFS volume that will not be replicated.  That of course only affects the VM’s paging files – not the guest VM’s paging files that are controlled by the OS.  I suspect that a healthy amount of changed data on the VMs are the paging files for the OS.  The amount of changed data on those VM’s looked suspiciously similar to the amount of RAM assigned to the VM.  There typically is some correlation to how much RAM an OS has to run with, and the size of the page file.  This is pure speculation at this point, but certainly worth looking into.

The next logical step would be to figure out what could be done to reconfigure VM’s to perhaps place their paging/swap files in a different, non-replicated location.   Two issues come to mind when I think about this step. 

1.)  This adds an unknown amount of complexity (for deploying, and restoring) to the systems running.  You’d have to be confident in the behavior of each OS type when it comes to restoring from a replica where it expects to see a page file in a certain location, but does not.  How scalable this approach is would also need to be asked.  It might be okay for a few machines, but how about a few hundred?  I don’t know.

2.)  It is unknown as to how much of a payoff there will be.  If the amount of data per VM gets reduced by say, 80%, then that would be pretty good incentive.  If it’s more like 10%, then not so much.  It’s disappointing that there seems to be only marginal documentation on making such changes.  I will look to test this when I have some time, and report anything interesting that I find along the way.

 

The fires… unrelated, and related

One of the first problems to surface recently were issues with my 6224 switches.  These were the switches that I put in place of our 5424 switches to provide better expandability.  Well, something wasn’t configured correctly, because the retransmit ratio was high enough that SANHQ actually notified me of the issue.  I wasn’t about to overlook this, and reported it to the EqualLogic Support Team immediately.

I was able to get these numbers under control by reconfiguring the NIC’s on my ESX hosts to talk to the SAN with standard frames.  Not a long term fix, but for the sake of the stability of the network, the most prudent step for now.

After working with the 6224’s, they do seem to behave noticeably different than the 5242’s.  They are more difficult to configure, and the suggested configurations from the Dell documentation seem were more convoluted and contradictory.  Multiple documents and deployment guides had inconsistent information.  Technical Support from Dell/EqualLogic has been great in helping me determine what the issue is.  Unfortunately some of the potential fixes can be very difficult to execute.  Firmware updates on a stacked set of 6224’s will result in the ENTIRE stack rebooting, so you have to shut down virtually everything if you want to update the firmware.  The ultimate fix for this would be a revamp of the deployment guides (or lets try just one deployment guide) for the 6224’s that nullifies any previous documentation.  By way of comparison, the 5424 switches were, and are very easy to deploy. 

The other issue that came up was some unexpected behavior regarding replication, and it’s use of free pool space.  I don’t have any empirical evidence to tie these two together, but this is what I had observed.

During this past month in which I had an old physical storage server fail on me, there was a moment where I had to provision what was going to be a replacement for this box, as I wasn’t even sure if the old physical server was going to be recoverable.  Unfortunately, I didn’t have a whole lot of free pool space on my array, so I had to trim things up a bit, to get it to squeeze on there.  Once I did, I noticed all sorts of weird behavior.

1.  Since my replication jobs (with ASM/ME and ASM/VE) leverage the free pool space for the creation of temporary replica/snap that is created on the source array, this caused problems.  The biggest one was that my Exchange server would completely freeze during it’s ASM/ME snapshot process.  Perhaps I had this coming to me, because I deliberately configured it to use free pool space (as opposed to a replica reserve) for it’s replication.  How it behaved caught me off guard, and made it interesting enough for me to never want to cut it close on free pool space again.

2.  ASM/VE replica jobs also seems to behave odd with very little free pool space.  Again, this was self inflicted because of my configuration settings.  It left me desiring a feature that would allow you to set a threshold so that in the event of x amount of free pool space remaining, replication jobs would simply not run.  This goes for ASM/VE and ASM/ME.

Once I recovered that failed physical system, I was able to remove that VM I set aside for emergency turn up.  That increased my free pool space back up over 1TB, and all worked well from that point on. 

 

Timing

Lastly, one subject matter came up that doesn’t show up in any deployment guide I’ve seen.  The timing of all this protection shouldn’t be overlooked.  One wouldn’t want to stack several replication jobs on top of each other that use the same free pool space, but haven’t had the time to replicate.  Other snapshot jobs, replicas, consistency checks, traditional backups, etc should be well coordinated to keep overlap to a minimum.  If you are limited on resources, you may also be able to use timing to your advantage.  For instance, set your daily replica of your Exchange database to occur at 5:00am, and your daily snapshot to occur at 5:00pm.  That way, you have reduced your maximum loss period from 24 hours to 12 hours, just by offsetting the times.

Replication with an EqualLogic SAN; Part 3

 

In parts one and two of my journey in deploying replication between two EqualLogic PS arrays, I described some of the factors that came into play on how my topology would be designed, and the preparation that needed to occur to get to the point of testing the replication functions. 

Since my primary objective of this project was to provide offsite protection of my VMs and data in the event of a disaster at my primary facility,  I’ve limited my tests to validating that the data is recoverable from or at the remote site.   The logistics of failing over to a remote site (via tools like Site Recovery Manager) is way outside the scope of what I’m attempting to accomplish right now.  That will certainly be a fun project to work on some day, but for now, I’ll be content with knowing my data is replicating offsite successfully.

With that out of the way, let the testing begin…

 

Replication using Group Manager 

Just like snapshots, replication using the EqualLogic Group Manager is pretty straight forward.  However, in my case, using this mechanism would not produce snapshots or replicas that are file-system consistent of VM datastores, and would only be reliable for data that was not being accessed, or VM’s that were turned off.  So for the sake of brevity, I’m going to skip these tests.

 

ASM/ME Replica creation.

My ASM/ME replication tests will simulate how I plan on replicating the guest attached volumes within VMs.  Remember, these are replicas of the guest attached volumes  only – not of the VM. 

On each VM where I have guest attached volumes and the HITKit installed (Exchange, SQL, file servers, etc.) I launched ASM/ME to configure and create the new replicas.  I’ve scheduled them to occur at a time separate from the daily snapshots.

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As you can see, there are two different icons used; one represents snapshots, and the other representing replicas.  Each snapshot and replica will show that the guest attached volumes (in this case, “E:\” and “F:\” )  have been protected using the Exchange VSS writer.  The two drives are being captured because I created the job from a “Collection” which makes most sense for Exchange and SQL systems that have DB files and transaction log data that you’d want to capture at the exact same time.  For the time being, I’m just letting them run once a day to collect some data on replication sizes.  ASM/ME is where recovery tasks would be performed on the guest attached volumes.

A tip for those who are running ASM/ME for Smartcopy snapshots or replication.  Define in your schedules a “keep count” number of snapshots or replicas that fall within the amount of snapshot reserve you have for that volume.  Otherwise, ASM/ME may take a very long time to start  the console and reconcile the existing smart copies, and you will also find those old snapshots in the “broken” container of ASM/ME.    The startup delay can be so long, it almost looks as if the application has hung, but it has not, so be patient.  (By the way, ASM/VE version 2.0, which should be used to protect your VMs, does not have any sort of “keep count” mechanism.  Lets keep our fingers crossed for that feature in version 3.0)

 

ASM/ME Replica restores

Working with replicas using ASM/ME is about as easy as it gets.  Just highlight the replica, and click on “Mount as read-only.”  Unlike a snapshot, you do not have the option to “restore” over the existing volume when its a replica.

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ASM/ME will ask for a drive letter to assign that cloned replica to.  Once it’s mounted, you may do with the data as you wish.  Note that it will be in a read only state.  This can be changed later if needed.

When you are finished with the replica, you can click on the “Unmount and Resume Replication…”

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ASM/ME will ask you if you want to keep the replica around after you unmount it.  To keep it, uncheck the box next to “Delete snapshot from the PS Series group…”

 

ASM/VE replica creation

ASM/VE replication, which will be the tool I use to protect my VMs, took a bit more time to set up correctly due to the way that ASM/VE likes to work.  I somehow missed the fact that one needed a second ASM/VE server to run at the target/offsite location for the ASM/VE server at the primary site to communicate with.  ASM/VE also seems to be hyper-sensitive to the version of Java installed on the ASM/VE servers.  Don’t get too anxious on updating to the latest version of Java.   Stick with a version recommended by EqualLogic.  I’m not sure what that officially would be, but I have been told by Tech Support that version 1.6 Update 18 is safe.

Unlike creating Smartcopy snapshots in ASM/VE, you cannot use the “Virtual Machines” view in ASM/VE to create Smartcopy replicas.  Only Datastores, Datacenters, and Clusters support replicas.  In my case, I will click  “Datastores” view to create Replicas.  Since I made the adjustments to where my VM’s were placed in the datastores, (see part 2, under “Preparing VMs for Replication”) it will still be clear as to which VMs will be replicated. 

image

After creating a Smartcopy replica of one of the datastores, I went to see how it looked.  In ASM/VE it appeared to complete successfully, and in SANHQ it also seemed to indicate a successful replica.  ASM/VE then gave a message of “contacting ASM peer” in the “replica status” column.  I’ve seen this occur right after I kicked off a replication job, but on successful jobs, it will disappear shortly.  If it doesn’t disappear, this can be a configuration issue (user accounts used to establish the connection due to known issues with ASM/VE 2.0), or caused by Java.

 

ASM/VE replica restores

At first, ASM/VE Smartcopy replicas didn’t make much sense to me, especially when it came to restores.  Perhaps I was attempting to think of them as a long distance snapshot, or that they might behave in the same way as ASM/ME replicas.  They work a bit  differently than that.  It’s not complicated, just different.

To work with the Smartcopy replica, you must first log into the ASM/VE server at the remote site.  From there, click on “Replication” > “Inbound Replicas” highlighting the replica from the datastore you are interested in.  Then it will present you with the options of “Failover from replica” and “clone from replica”  If you attempt to do this from the ASM/VE server from the primary site, these options never present themselves.  It makes sense to me after the fact, but took me a few tries to figure that out.  For my testing purposes, I’m focusing exclusively on “clone from replica.”  The EqualLogic documentation has good information on when each option can be used.

When choosing “Clone from Replica” it will have a checkbox for “Register new virtual machines.”  In my case, I uncheck this box, as my remote site will have just a few hosts running ESXi, and will not have a vCenter server to contact.

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Once it is complete, access will need to be granted for the remote host in which you will want to try to mount the volume.  This can be accomplished by logging into the Group Manager of the target/offsite SAN group, selecting the cloned volume, and entering CHAP credentials, the IP address of the remote host, or the iSCSI initiator name. 

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Jump right on over to the vSphere client for the remote host, and under “Configuration” > “Storage Adapters”  right click on your iSCSI software adapter, and select “Rescan”  When complete, go to “Configuration” > “Storage” and you will notice that it the volume does NOT show up.  Click “Add Storage” > “Disk/LUN”

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When a datastore is recognized as a snapshot, it will present you with the following options.  See http://www.vmware.com/pdf/vsphere4/r40/vsp_40_iscsi_san_cfg.pdf for more information on which option to choose.

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Once completed, the datastore that was replicated to the remote site and cloned so that it can be made available to the remote ESX/i host, should now be visible in “Datastores.” 

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From there just browse the Datastore, drilling down to the folder of the VM you wish to turn up, highlight and right click the .vmx file, and select “Add to inventory.”  Your replicated VM should now be ready for you to power up.

If you are going to be cloning a VM replica living on the target array to a datastore, you will need to do one additional step if any of the VM’s have guest attached volumes using the guest iSCSI initiator.  At the target location, open up Group Manager, and drill down to “Replication Partners” > “[partnername]” and highlight the “Inbound” tab.  Expand the volume(s) that are associated with that VM.  Highlight the replica that you want, then click on “Clone replica”

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This will allow you to reattach a guest attached volume to that VM.  Remember that I’m using the cloning feature simply to verify that my VM’s and data are replicating as they should.  Turning up systems for offsite use is a completely different ballgame, and not my goal – for right now anyway.

Depending on how you have your security and topology set up, and how connected your ESX host is offsite, your test VM you just turned up at the remote site may have the ability to contact Active Directory at your primary site, or guest attached volumes at your primary site.  This can cause problems for obvious reasons, so be careful to not let either one of those happen.  

 

Summary

While demonstrating some of these capabilities recently to the company, the audience (Developers, Managers, etc.) was very impressed with the demonstration, but their questions reminded me of just how little they understood the new model of virtualization, and shared storage.  This can be especially frustrating for Software Developers, who generally consider that there isn’t anything in IT that they don’t understand or know about.  They walked away impressed, and confused.  Mission accomplished.

Now that I’ve confirmed that my data and VM’s are replicating correctly, I’ll be building up some of my physical topology so that the offsite equipment has something to hook up to.  That will give me a chance to collect some some statistics on replication, which I will share on the next post.

Replication with an EqualLogic SAN; Part 2

 

In part 1 of this series, I outlined the decisions made in order to build a replicated environment.  On to the next step.  Racking up the equipment, migrating my data, and laying some groundwork for testing replication.

While waiting for the new equipment to arrive, I wanted to take care of a few things first:

1.  Update my existing PS5000E array up to the latest firmware.  This has never been a problem, other than the times that I’ve forgotten to log in as the default  ‘grpadmin’ account (the only account allowed to do firmware updates).  The process is slick, with no perceived interruption.

2.  Map out how my connections should be hooked up on the switches.  Redundant switches can only be redundant if you plug everything in the correct way.

3.  IP addressing.  It’s all too easy just to randomly assign IP addresses to a SAN.  It may be it’s own isolated network, but in the spirit of “design as if you know its going to change”  it might just be worth observing good addressing practices.  My SAN is on a /24 net block.  But I configure my IP addresses to respect potential address boundaries within that address range.  This is so that I can subnet or VLAN them down (e.g. /28)  later on, as well as helping to simplify rule sets on my ISA server that are based on address boundaries, and not a scattering of addresses.

Preparing the new array

Once the equipment arrived, it made most sense to get the latest firmware on the new array.  The quickest way is to set it up temporarily using the “initialize PS series  array” feature in the “Remote Setup Wizard” of the EqualLogic HITKit on a machine that can access the array.  Make it it’s own group, update the firmware, then reset the array to the factory defaults.  After completing the update and  typing “reset”  up comes the most interesting confirmation prompt you’ll ever see.  Instead of “Reset this array to factory defaults?”  [Y/N]”  where a “Y” or “N” is required, the prompt is “Reset this array to factory defaults? [n/DeleteAllMyDataNow]”  You can’t say that isn’t clear.  I applaud EqualLogic for making this very clear.  Wiping a SAN array clean is serious stuff, and definitely should be harder than typing a “Y” after the word “reset.” 

After the unit was reset, I was ready to join it to the existing group temporarily so that I could evacuate all of the data from the old array, and have it placed on the new array.  I plugged all of the array ports into the SAN switches, and turned it on.  Using the Remote Setup Wizard, I initialized the array, joined it to the group, then assigned and activated the rest of the NICs.   To migrate all of the data from one array to another, highlight the member with the data on it, then  click on “Delete Member”  Perhaps EqualLogic will revisit this term.  “Delete” just implies way too many things that doesn’t relate to this task.

The process of migrating data chugs along nicely.  VM’s and end users are none-the-wiser.  Once it is complete, the old array will remove itself from the group, and reset itself to the factory defaults.  It’s really impressive.  Actually, the speed and simplicity of the process gave me confidence when we need to add additional storage.

When the old array was back to it’s factory defaults,  I went back to initialize the array, and set it up as a new member in a new group.  This would be my new group that would be used for some preliminary replication testing, and will eventually live at the offsite location.

As for how this process compares with competing products, I’m the wrong guy to ask.  I’ve had zero experience with Fiber Channel SANs, and iSCSI SANs from other vendors.  But what I can say is that it was easy, and fast.

After configuring the replication between the two group, which consisted of configuring a few shared passwords between the the two groups, and configuring replication to occur on each volume, I was ready to try it out  …Almost.

 

Snapshots, and replication.

It’s worth taking a step back to review a few things on snapshots and how the EqualLogic handles them.  Replicas appear to work in a similar (but not exact) manner to snapshots, so many of the same principals apply.  Remember that snapshots can be made in several ways.

1.  The most basic are snapshots created in the EqualLogic group Manager.  These do exactly as they say, making a snapshot of the volume.  The problem is that they are not file-system consistent of VM datastores, and would only  be suitable for datastores in which all of the VM’s were turned off at the time the snapshot was made.

2.  To protect VM’s, “Autosnapshot manager VMware Edition” (ASM/VE) provides and ability to create a point-in-time snapshot, leveraging vCenter through VMware’s API, then does some nice tricks to make this an independent snapshot (well, of the datastore anyway) that you see in the EqualLogic group manager, under each respective volume.

3.  For VM’s with guest iscsi attached drives, there is “Autosnapshot Manager Microsoft Edition” (ASM/ME).  This great tool is installed with the Host Integration Toolkit (HITkit).  This makes application aware snapshots by taking advantage of the Microsoft Volume Shadow Copy Service Provider.  This is key for protecting SQL databases, Exchange databases, and even flat-file storage residing on guest attached drives.  It insures that all I/O is flushed when the snapshot is created.  I’ve grown quite partial to this type of snapshot, as its nearly instant, no interruption to the end users or services, and provides easy recoverability.  The downside is that it can only protect data on iscsi attached drives within the VM’s guest iscsi initiator, and must have a VSS writer specific to an application (e.g. Exchange, SQL) in order for it to talk correctly.  You cannot protect the VM itself with this type of snapshot.  Also, vCenter is generally unaware of these types of guest attached drives, so VCB backups and other apps that rely on vCenter won’t include these types of volumes.

So just as I use ASM/ME for smartcopy snapshots of my guest attached drives, and ASM/VE for my VM snapshots, I will use these tools in the similar way to create VM and application aware replica’s of the VM’s and the data.

ASM/VE tip:  Smartcopy snapshots using ASM/VE give the option to “Include PS series volumes accessed by guest iSCSI initiators.”  I do not use this option for a few very good reasons, and rely completely on ASM/ME for properly capturing guest attached volumes. 

Default replication settings in EqualLogic Group Manager

When one first configures a volume for replication, some of the EqualLogic defaults are set very generous.  The two settings to look out for are the “Total replica reserve” and the “Local replication reserve.”  The result is that these very conservative settings can chew up a lot of your free space on your SAN.  Assuming you have a decent amount of free space in your storage pool, and you choose to stagger some of your replication to occur at various times of the day, you can reduce the “Local replication reserve” down to it’s minimum, then click the checkbox for “allow temporary use of free pool space.”  This will minimize the impact of enabling replication on your array.

 

Preparing VM’s for replication

There were a few things I needed to do to prepare my VM’s to be replicated.  I wasn’t going to tackle all optimization techniques at this time, but thought it be best to get some of the easy things out of the way first.

1.  Reconfigure VM’s so that swap file is NOT in the same directory as the other VM files.  (This is the swap file for the VM at the hypervisor level; not to be confused with the guest OS swap file.)  First I created a volume in the EqualLogic group manager that would be dedicated for VM swap files, then made sure it was visible to each ESX host.  Then, simply configure the swap location at the cluster level in vCenter, followed by changing the setting on each ESX host.  The final step will be to power off and power on of each VM.  (A restart/reboot will not work for this step).  Once this is completed, you’ve eliminated a sizeable amount of data that doesn’t need to be replicated.

2.  Revamp datastores to reflect good practices with ASM/VE.  (I’d say “best practices” but I’m not sure if they exist, or if these qualify as such).  This is a step that takes into consideration how ASM/VE works, and how I use ASM/VE.   I’ve chosen to make my datastores reflect how my VM’s are arranged in vCenter.    Below is a screenshot in vCenter of the folders that contain all of my VMs.

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Each folder has VMs in it that reside in just one particular datastore.  So for instance, the “Prodsystems-Dev” has a half dozen VM’s exclusively for our Development team.  These all reside in one datastore called VMFS05DS.  When a scheduled snapshot of a vcenter folder (e.g. “Prodsystems-Dev”) using ASM/VE, it will only hit those VM’s in that vcenter folder, and the single datastore that they reside on.  If it is not done this way, an ASM/VE snapshot of a folder containing VM’s that reside in different datastores will generate snapshots in each datastore.  This becomes terribly confusing to administer, especially when trying to recover a VM.

Since I recreated many of my volumes and datastores, I also jumped on the opportunity to make these new datastores with a 4MB block size instead of the the default 1MB block size.  Not really necessary in my situation, but based on the link here, it seems like a a good idea.

Once the volumes and the datastores were created and sized the way I desired, I used the storage vmotion function in vCenter to move each VM into the appropriate datastore to mimic my arrangement of folders in vCenter.  Because I’m sizing my datastores for a functional purpose, I have a mix of large and small datastores.  I probably would have made these the same size if it weren’t for how ASM/VE works.

The datastores are in place, and now mimic the arrangement of folders of VM’s in vCenter.  Now I’m ready to do a little test replication.  I’ll save that for the next post.

Suggested reading

Michael Ellerbeck has some great posts on his experiences with EqualLogic, replication, Dell switches, and optimization.    A lot of good links within the posts.
http://michaelellerbeck.com/

The Dell/EqualLogic Document Center has some good overview documents on how these components work together.  Lots of pretty pictures. 
http://www.equallogic.com/resourcecenter/documentcenter.aspx

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