Equallogic + Exchange (ASM does not truncate logs!)

Nobody is questioning the snap part. Yes, EQL snaps work. They are MASSIVE for Exchange, because of your large 16M page size, but lets not muddy the water.

The ASM/HIT it worthless for backup, as it does not clear logs.

You need another tool, and therefore another process to lift and shift data from the disks. If you want the backup to be a weekly backup (which is typical with a snapshotted NAS environment, particularly when offices are 9-5) then with EQL you have to store the LOGS ** ALL WEEK ** until the backup runs and clears the logs.

This is compounded by the EQL Exchange Snapshots being almost the same size as the base data due to your 16M page file. A well documented weakness of EQL.

 

With NetApp, not only do they _not_ suffer from the massive snapshots size like EQL (although I agree, WAFL is, in itself an overhead) but they clear the logs. You can then use a tool weekly to NDMP dump the data, but the logs don't sit around all week taking up expensive disk space.

 

Most people in here, if they don't run a backup everyday, will soon realise that this is going to be very expensive (Exchange) on EQL, as you will need 5 times the storage size you thought you needed, to A) keep the logs, and B) store the massive Exchange snapshots you suffer from. It's either that or do a full backup everyday, in which case you may have well just stuck with DAS. The benefit of NAS should be the snapshot based backup.

Although NetApp isn't cheap, due to the ASM weakness of not following MS advice on said article which says YOU SHOULD purge the logs, but your 16M page eats disk space on copy on write snapshots makes EQL even more expensive. EQL should a long time ago just written into the ASM to purge the logs, like NetApp SnapManager for Exchange purges the logs. There is no excuse for it. I suspect all this defensive waffle from EQL is because they just can't code it, as the guy who made the ASM and HIT kit left during the Dell / Equallogic assimiliation.

 

 

 

I'm happy for you to disagree Don, and its valiant of you to attempt to defend the indefensible.

I'm just hoping my posts save other people from going down the same dark alley as I did with Equallogic. I wanted Equallogic to work for us I really did.

The UI for managing the box is great. Implementation is simple (compared to a NetApp install). There is a lot going for it. But that initial excitement soon wanes when you realise the software layer is not deep from Equallogic.  (Almost worthless in my book, cos if the ASM/HIT kit won't do what we need, (which it doesnt) you may as well just leverage the software layer from a 3rd party in its entirety. Which by virtue means the ASM/HIT kit is worthless to the client.). With EMC or NetApp you will get tools from the same vendor to snap on disk, purge logs and move on. 

I do disagree with your NAS versus block storage stance though. The ASM/HIT runs in the host, so is well aware of the underlying file system, as it is just using Microsoft API calls in VSS's case. And as I _keep stating_ to be fully VSS compliant, you SHOULD purge the logs that are committed post snap (Its in the link Ive already sent). Equallogic by religiously sticking to their guns on this is ultimately the reason this year we will replace all our Equallogic kit with NetApp. 

With EMC or NetApp you will get tools from the same vendor to snap on disk, purge logs and move on.

As a customer of both, I find this statement hard to parse.  We are certainly are free to license the appropriate NetApp software, at several thousands of dollars per host. 

First sentence.  "Backup Application".  ASM/ME is not a backup application and never claimed to be.  No where in the manual do we say use ASM/ME for backups. Snapshots do not equal a backup strategy.  Since they reside on the same disks as the base volume.   However, if you use a backup application that supports VSS, then you get your truncate.

Don,

What does it mean when dozens of tech reports (but not manuals) that refer to using ASM/ME for "Data Protection" ?  Should they be revised to say "Data protection [but not backup per MS]" ?  Simple example:

http://www.equallogic.com/resourcecenter/assetview.aspx?id=9705

No one is suggesting its a replacement for a backup program.

You should purge logs (as is recommended) and *other vendors do* 

We do off host at the weekend. During the week, I want to snap, and remove logs. Equallogic don't remove committed logs, as MS say you SHOULD.

And as I say again, if you are going to use 3rd party products (we do for the off host) then you may as well use it every day, and remove the need for ASM/HIT effectively then the ASM/HIT is worthless, as I use the backup tool to do the weekly off host, and schedule a daily VSS snap.(We are trialling our backup vendors Exchange tool which calls on VSS to see if it does a full VSS job and purge logs, until we move ourselves off of Equallogic)

Enough words. Here is the diagram that illustrates the problem.

http://steveesg.posterous.com/equallogic-issue

 

Due to the 2 issues (I didn't want to bring snapshot size into it, but as a whole it compounds the issue)

 

We can afford the NetApp tool, as we won't need all the wasted space of both the large snapshot sizes (admittedly WAFL will be an overhead) but also the log files will get purged every night, and we can backup weekly like we intended to and cut down our shelves/space etc. 

Equallogic has ** 2 ** big weaknesses, large Exchange snapshot sizes & their ASM/HIT tool does not purge logs.

(I am not the only one to observe this: See snapshot reference on this good article on Equallogic: http://www.tuxyturvy.com/blog/index.php?/archives/49-All-things-being-Equallogic.html)

We've discussed the fact you don't purge logs add infinitum. 

 

 

I'm happy for you to disagree Don, and its valiant of you to attempt to defend the indefensible. I'm just hoping my posts save other people from going down the same dark alley as I did with Equallogic. I wanted Equallogic to work for us I really did.

You just aren't understanding it. You keep hearing that this is not what it is for and you keep insisting that Netapp does it. Stop trolling. ASM doesn't play video either.

Do your full backups that you will hopefully never ever use again to clean your own logs every so often or turn on circular logging if you are foolish enough to think you don't have to. Anyone who has ever spend HOURS doing a full restore of exchange can see the value of snapping the database and doing the verfication on it well in advance of when you need it.

Ramtek, you clearly didn't read the thread properly. I don't want to "backup", I want a database consistent snapshot that I can recover from (the whole point of NAS based technology, or you would probably just get a bunch of inexpensive disks) Full backups are copying data "somewhere else" (time consuming), snapshots mean the data "copy" (snap/quick) is kept on the same stack of disks. SnapManager for Exchange for example, snapshots Exchange (via VSS) , you can recover from it (either fully, or brick level) . You clearly haven't used NAS (or SAN) technology to do a speedy restore of Exchange, we do it all the time - including Equallogic! but we just don't want the commited logs left on disk, that MICROSOFT! say shouldn't happen if you are fully VSS compliant as per the KB article I posted.

I'm happy for anyone to visit our office, and I can demonstrate the problem first hand, and show you how it works on NetApp.

We will be migrating to NetApp over the next 6 months. I will come back and post my findings once we move over. I'm hoping we no longer suffer from Exchange snapshots that are 90% of the base data, but only a system under our production load will give us the real number on this.

And that the logs get truncated which we've tested and know works, which makes us really frustrated that Equallogic isn't fully VSS compliant like NetApp are.

 

 

 

 

Clearly you didn't RTM or haven't actually recoved using a snapshot taken by ASM. Why don't your actually try it before you post back. Have you mounted a snapshot and looked at it? What do you think happens inside those little commandlines you used to have to issue yourself? Enough with sophmoric posts. Please go buy NetApp and stop trolling here. We have both and one is clearly more expensive and irritating but if it doesn't trigger your OCD you should use it.

 

 

 

Sophmoric? You're slinging personal insults, which I refrained from, I don't wish to lower myself to your level. I wasn't trolling, I was stating _fact_, the ASM+HIT kit do not truncate the logs. Plain, and very simple.

I suspect you are a technical guy working in a technical team, given the language you use and the tone you are expressing.

Yes we have mounted snapshots, and we recover from them with Ontrack Powertools frequently. Not sure where you are going with that we haven't tried it as your post was not very readable.

If you have any dealing on the commercial side, you wouldn't have made the statement about NetApp being more expensive. 

The difference between support/health checks/software layer are clear to see. But I'm not Equallogic bashing in general, as it did what we wanted to do with VMWare just fine, its just the ASM+HIT kit we have the real issues with. 

I have no idea what the RTM comment about reading the manual is all about, but answering you is doing little to further the value of debate here.

I was hoping either another customer with real knowledge had some insight, or a Dell/Equallogic rep would answer with hope / reasons.

I'm also very glad to point out to potential customers that the large snapshot sizes using Exchange (I'm not trolling, I'm not the only customer to suffer from this, I put a link in an earlier post, and there are other blogs online referencing the same issue) plus the fact the ASM+HIT kit not truncating logs is a real space killer. We ended up buying more disk than we needed due to this weekness meaning that NetApp will be cheaper over all.

So, I have been there and done it, we do own both, and I willing for anyone to come to our office and see if it for themselves. We aren't security sensitive, so I am more than happy to show potential customers the differences, for the sake of them having a better quality operational life and saving them the frustrations we have experienced.

 

 

The ability to truncate Exchange Transaction Logs without a 3rd party backup application was added to Exchange 2007 SP2 and later. 

For what its worth, after 15+ years of managing exchange servers, and various incarnations of 3rd party backup applications for Exchange, it was ASM/ME and it's ability to create a fully application aware snap that has saved my rear.  I wrote about one of these incidents here.

How you choose to maintain your transaction log sizes is up to you.