There are many reasons i could say that the DD is better than the HP D2D.. First thing with the D2D you need to create multiple or extended "blackout windows" for processing, things like reclimation, restores, tape copies (should you need them).
When a D2D is doing backups and a restore is needed all the backups come to a CRAWL while the restore happens, or the flip side the Restore crawls and the backup still slow down.
While recplimation is happening NOTHING can be happeneing, if you attempt to run a backup or restore then the D2D will likley just kill the backup causing some random untracable error.
The D2D's error logs are misserable, rarely anything useful and the interface is really terrible, If you are using OST there is no real OST menu option in the GUI. You need to configure CIFS authentication and shares with specific names, once you configure the shares and users, you assign them manually to the share and have to RESTART the D2D so it allows access.
Talking about Support, my experience may have been a unique one however when i called to ask support about OST or Openstorage with Symantec (mainly i needed the OST plugin since it was not provided) the tech didnt know what OST was... He told me repeatedly that i needed to call Symantec for the OST plugin since its their product?? After about 2 weeks of searching through our partners we found a guy who knew what OST was and was able to help.
OK Enough bashing on the D2D (though they make it easy)
DataDomain, Useing either OST/VTL/CIFS/NFS with NBU i have had little issues to be honest. I think it has something to do with the whole you get what you pay for thing. The DD is ALOT more expencive than a D2D however you are getting alot more bang for the buck. A DD does not require a blackout window for maintenance processing, Support is usually helpful (at least they know what im talking about when i call them) OST is fully supported and thier Site Documentation is easy to navigate.
Now so i dont sound like im just bashing on D2D, the Datadomain really does rely on multiple backup streams to truly get the advertised speeds, something like 20-50 streams is usually best. If 10G i an option then all 200 Streams can be used and usually not see much degredation in speeds.
Data Domain does take a performance hit when doing simultanious processing such as Restore and backup at the same time, but the jobs still run and when the restore or backups finish you will get the throughput back on the ladder.
I hope this is at least kind of helpfull to you.
DataDomain with the new 5.x version of the software solves many of the GUI issues and lack of management features from the GUI that normally you had to do via CLI. I believe the CIFS restarting issue is completely resolved in 5.0. I did it recently, enabled CIFS, created a share and did not have to reboot the DD box. Though I did have to reboot a couple of hosts that didn't want to see the share...
As for error messages, the support team is actually VERY VERY good. Often solving most cases within a day or two, with simple config questions the same day. You can't say the same about HP's support. Documentation is also very good too.
What's great about the DataDomain units, is they are VERY flexible. You can use VTL, CIFS, NFS, OST and CIFS all at the same time. HP is either or and many other vendors too. So I can backup a mainframe using the VTL, do NFS mounts for my Oracle databases, dump SQL to CIFS shares, and use OST for my backup applications. All at the same time.
The reclamation thing i feel is a non-issue. By default it's set to 2am on Wed. Change it to daytime hours and problem solved. As often, you are not doing backups during the day.
Performance has always been very very good on the DD boxes I've sold or administered. I've got many customers getting 150-400MB/s depending on their setup. Some use OST, others uses NFS and VTL.
While it costs the MOST out of all the other vendors, it also works, works better, works faster, and is the most flexible unit out there. I've also been able to compare the DataDomain units to other dedupe products, and in almost all cases, the dedupe ratio has been better by a large margin. Meaning disk for disk, the DD boxes require less of it.
Some of the info here appears to be incorrect regarding the HP d2d. I recommend you call your local HP sales office and speak to a product specialist. A few comments: d2d can [also] do VTL, CIFS and NFS, with both backup and restore, all at once. If using NBU or BE, can also do OST to manage replication and restores. The latest product announced offers HA and multi-node scaling. No reboot is needed following config of shares. CIFS AD and user auth is supported (as well as none).
Hope this helps.
You might also want to consider Exagrid, we opted for them after being shocked at the price of the DataDomain quote we received. Their architecture may result in more physical disks being on-site, but the price was significantly lower than DD, and it's meeting our needs just fine, setting up OST to it from NetBackup was very easy.
Seth.. Exagri here is very expecive because of the taxes,
Soo.. at this moment DD is the better choice?
d2d seccond place
Quantum the third one?
The DD models are the most mature on the market. Everything they do pretty much works as advertised. It's hard to put a price on that. yes it's the most expensive, but you'll probably spend less time with support otherwise. Not to mention, less power consumed, less rack space, more flexibility.
I'm not sure I would put HP 2nd, perhaps Exagrid due to their maturity in the market place. HP 3rd.
Quantum has a long road ahead of them in delivering and executing on their promises.
The important thing is to test, test, test. The nuances of each should come out in just a few simple tests to verify dedupe performance.
Outside of that, there are a couple of other vendors out there, and some coming up too. But when your business is buying last defense to backing up data, the new kid on the block, shouldn't be considered.