Wednesday, May 21, 2008

Why Is Mozy So Slow?

I have good backup habits. At least I do now.

I hate to admit it, but it took losing not one, but two, hard disks (one to a hardware failure, the other to a particularly virulent virus with a rootkit) and some critical data to get me there. But I'm all better now. Really.

I have a USB hard disk that I do full backups to and I use Mozy (the paid version) for offsite backups of critical stuff. I used to use Carbonite but felt it was slow and it lacked configuration options that I wanted. And Mozy works great for my wife, whose total backup is less than 2GB. But, for me, Mozy slows my machine down to a crawl whenever a backup starts.

Now, I know I have a big backup. It's currently 157,070 files for a total of 84GB. And that isn't even everything. I have hundreds of gigabytes of photos that aren't in my Mozy backup set. Most of what I have backed up isn't changing on a regular basis.

How slow is it?

Here are some examples.

Opening the Mozy Configuration window (just opening it!) takes 20 minutes. Note that you have to open the Configuration window to change any settings or get status information on previous backups.

The backup itself takes hours to days. A small backup, 290 files totaling 75MB, took 4 hours. Of this time, almost all of the time was spent scanning my hard disk and compressing files for backup. The actual transfer took only 3 minutes.

A backup of 1000 digital photos totaling 5GB took took more than 4 days (that's with the machine on, nonstop). Of that time, 47 hours were prep and only 8 hours were transfer. What was it doing for 47 hours?!

To make matters worse, any interruption of the backup (like hibernating my machine or losing a network connection) looks like it restarts the whole thing.
Where's the slowdown?

Let's look at the transfer speed first. 5GB over 8 hours is only 625MB per hour, which is about 10% of my upstream capacity. So, it's obviously not network constrained.

Could it be CPU or disk constrained? It's hard to separate the two without a deeper analysis that I can't do easily, but I have a good way to look at the overall picture. For my USB backups, I use SyncBackSE from 2BrightSparks, which I like very much -- unlike most so-called sync products, SyncBackSE actually knows how to do a true sync operation, including dealing with conflicts. And it's great for backups. A backup of almost 3,000 files totaling 6GB took just 34 minutes from start to finish, including 16 minutes scanning 460,000 files (3x times the number in my Mozy backup set) and 18 minutes copying.

Mozy does seem to be doing way too much I/O. Looking in Task Manager, it looks like SyncBackSE reads and writes very little more (maybe 10% more) than the data being backed up. That's about what I would expect. But Mozy's two processes (mozybackup.exe and mozystat.exe) read more than 15 bytes for every byte being backed up and write about 2 bytes for every byte being backed up, and that's excluding the network I/O. And it also looks like they are writing tiny packets to their server (an average of 8 bytes per Other I/O request). This certainly doesn't seem right to me.

Except for the backup that took 4 days, all of the Mozy backups occurred in the middle of the night while I wasn't using the machine, so there was no contention on the machine. Mozy does have an option for how much CPU it will consume. But, it doesn't seem to make much of a difference when I told Mozy it could have as much CPU as it wanted, either in how fast the backup happens or in the performance of my machine (it makes it crawl, either way). Remember, it takes 20 minutes of waiting for the Configuration window to open in order to change that option. To be fair, SyncBackSE also slows the machine down dramatically when it's running, but it's over a much shorter period of time.

I'm not expecting Mozy to be as fast as a local backup, but it's more than 100 times slower and there doesn't appear to be any reason for it. Mozy's scanning is 600 times(!) slower than SyncBackSE when it ought to be just as fast. I would guess, from what I can see, that Mozy stores the backup set database remotely instead of locally (why?), but that still shouldn't account for a 600x difference. Maybe Mozy needs to buy 2BrightSparks and use whatever it is they've done.

What's the answer?

I wish this blog post ended with an answer instead of a question, but I don't know the answer. Maybe the people at Mozy do. Maybe they'll enlighten us.

What I do know is that I have to look elsewhere. A full backup for me is already hundreds of gigabytes and growing fast. I use a 16GB card in my camera and, yes, I fill it sometimes. Add to that the huge, high-res Photoshop files that I create when I'm working on one of my montages.

I'm planning to look at FolderShare, BeInSync, and LogMeIn Backup. I have to say I don't really like the idea of paying a subscription fee to backup to my own hard disk, which I also have to find a remote server to put it on. Suggestions welcome.


Andrew M Greene said...

What I did was make a deal with a friend who also had an old Linux box in his basement. We each bought a really big hard drive, gave the other an account, and we set up rsync to back up to each other's basements.

This wouldn't scale as a commercial offering, but for two techies it was the cheapest, easiest, fastest way to go.

Unknown said...

I have been using ElephantDrive ( Its been great so far. No capping of upload speeds. Instant access to all files that have been uploaded even from other computers. And they recently released a Mac client which I have been playing with. Pretty neat.

Roy Leban said...

@nmhz: That's similar to FolderShare for Windows, which is looking like a pretty good candidate.

@neal: I'm wondering if Elephant Drive changed because I thought they had a limit in their "home" version, but now I see that it's 100GB transfer per month and unlimited total storage. If I can start with the Pro version to get everything up and then switch, it might be worth it. I had dismissed it because it is twice the price of Mozy and Carbonite, but if it's significantly better, it might be worth it.

The other newcomer that looks interesting is Syncplicity.

Travis Smith said...

I have ran into this as well, I am thinking the problem is that Mozy has to scan the files to see if any thing has changed and compare it to what it has on it server. But it has to encrypt and decrypt the files before doing so. This could be the reason. My backup on Mozy is 220 GB which is huge. So just a small backup of 100 MB takes about an hour from start to finish. That is really slow. But online storage is always going to be slow anyway!!

Anonymous said...

I had the same problem with slow uploads (8hrs for 247MB). I checked the configuration and noticed that the program had an option to enable a bandwith throttle from 7am - 9pm. Once I disabled that, my backup speed improved dramatically (going down to 30minutes for 247MB)

Unknown said...

Also, if you remove the predefined backup sets the configuration screen loads instantly. I just went and selected everything I wanted to backup directly through the File System tab.

My problem is my backups won't complete.

You should check out, This is the best cloud+desktop app I've seen in a long time. I'd be using them for complete backups as well if they offered a package above 50 GB. For now I just use it to share files between my computers and collaborate with co-workers. The free package is 2 GB and works on Mac + PC. It's great.

And here's a shameless plug for my site, Cityocracy, that will be launching soon. It's a blend between Yelp/Facebook/Craigslist.

AlexJB said...

hey Roy, thanks for posting this analysis! A year later, and Mozy's backup speed has not changed much. 48 hours for 6GB on my new account.

Mozy's reported upload speed matches speed tests from Speakeasy, and as it reports its incremental progress, it is indeed maxing that rate (somewhere around 400 kbps).

The catch, as you observed is a lot of I/O. A note in their support area FAQ mentions that Mozy is using a temp file on the C drive to encrypt/encode each file before uploading. There needs to be space on the C drive equal to 130% of the largest file that you have (this could explain why some folks are failing partway through).

Clearly, it's the encryption/encoding that is behind all the I/O. Why this is such a write-intensive action, I don't know; I don't know enough about encryption processes, but heavy encryption is known to inflate the file quite a bit, isn't it?

Not sure if Mozy is going to be an acceptable solution for me overall, given my file patterns (sets of photos will mean regular introduction of a hundreds of megs), but I'm not sure if there is a much faster solution out there... yet.

Roy Leban said...

@AlexJB. Thanks. I don't know if anybody from Mozy ever saw this post, but I've never heard anything from them.

Sadly all of the online backup programs have significant problems. A pretty disappointing lot.

Tony Ramirez said...

I too use SyncBackSE and it is great. It backups fast on my external drive but I wanted to try a offsite back.

Just tried Mozy Backup and it is the slowest thing I have ever used. Wasted $4.95 and tried it for about 30 minutes before cancelling my account and removing the program. It slows down my internet connection and my computer.

After it running for a half hour it only backed up a few megabites of files. It is now gone from my computer and I will stick with SyncBackSE.

Mum & Dad said...

Having read so many good reviews, I just signed-up for Mozy. What a waste of money! Mozy has been running for 18 hours on a PC that's running nothing else and it has only backed up 800Mb of the 8Gb I wanted backed-up. 800Mb in 18 hours! I know that online backups are slow, but if it was using my full bandwidth it should have completed by now.

msjgriffiths said...

Well, just to throw a wrench in the proceedings -

I just signed up for Mozy, and was looking for an explanation for why it didn't use a lot of network bandwidth. I came across this blog; another site, btw, said that Mozy encrypts 50 files or 50 MB, uploads, and then performs the next batch.

Still, I don't have a lot of complaints - I'm only uploading 17 GB, true, but it only took 6 hours for the first 9 GB and I expect the next 8 to be fairly fast. and if you don't generate more than a few hundred megs per day, it isn't a problem.

Unknown said...

I use Mozy and I agree that it's really slow, however I have been in contact with there technical support They suggested you change some programs in your services click the start button and in the search type in services, it should pop up at the top then change the following to automatic and click start on com+event systems, com+system application, Mozy, distributed transaction coordinator. It doesn't completly fix the problem but it does help significantly on the stops and starts of the backup. Also, disabling bandwidth throtaling helps a lot too. Compared to most other backup services, Moxy does have the best price and the most security for your files. I hope this helps.

Anonymous said...

I agree Mozy is slow. I notice my computer running Windows 7 with only 1GB of RAM takes a few extra minutes to load when I installed Mozy. Now that I uninstalled Mozy. My start up speed was back to normalt.

I prefer DropBox which is very simple to use, and has an option to not startup during boot. It is free and has 2 GB free plan.

I also don't like how Mozy adds a service to services.msc.

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