Thanks - I started my post before his second response which he posted before I came back to my computer.
With 16 GB it would be a very good idea that he check his page outs before investing in more RAM. I'm running with 16GB at work and typically have Photoshop (CS 5), Mail, Safari, FMPro and Word running at a all times along with other software that I move in and out during the day. I have minimal page outs.
I tested CrashPlan when it first became available for the Mac and decided that it was too CPU intensive for my 2007 computer. Perhaps it is still very CPU intensive and the user in interpretting the slowdown as a drive related when it is just a memory and CPU hog.
I nearly lost 100% of my data about 10 years ago when a hard drive failed, so I have been paranoid about backups ever since, which is why I use Dropbox, Crashplan, Time Machine and Carbon Copy Cloner. Each performs a slightly different function. They all access the hard drive, the first three going all day long.
IMO, therein lies the problem. Eliminate the paranoia and rely on one or two. If it was me, pick one of the first three and use it. Then, maybe two or three times a day, do a CCC incremental backup. For the other slowdowns, such as boot times, having so many things resuming during startup is the basic issue. I've reduced it to three or four things and booting into ML is two or three times slower than booting into SL.
For other speed issues, see:
Mac Maintenance Quick Assist,
Mac OS X speed FAQ,
Speeding up Macs,
How to Speed up Macs,
Macintosh OS X Routine Maintenance,
Mac troubleshooting: What to do when your computer is too slow,
Essential Mac Maintenance: Get set up,
Essential Mac Maintenance: Rev up your routines,
Maintaining OS X,
Five Mac maintenance myths and
Myths of required versus not required maintenance for Mac OS X for information.
Crashplan can be scheduled and maximum CPU usage can be adjusted for while you're working and while you're away, which I've done. Everything is pretty well optimized. My question seems to come down to, to what extent will the Fusion Drive add to all of the background activity that is slowing down my current system. I know it will be a lot faster but it still involves a large hard drive in addition to the 120 GB SSD.
I can't answer your question. Both on my new iMac and on the home brew Fusion drive that I played with after instructions appeared on the internet I've seen no evidence of slowdowns during heavy disk accesses. But I'm not making 3 backups at the same time. Your paranoia is probably part of your problem. But the reason I can't answer your question is because backing up is mostly going to involve reading the drive and comparing that to your existing backups. If your data extends beyond the SSD then obviously sometimes your backup programs will have to call data from the hard drive and there goes the advantage of the SSD. But what impact that would have overall I just can't say.
What I can tell you is this: I have two TimeMachine drives connected to my computer. When long backups occur (such as after I've applied an OS update) I sometimes get a warning that a TM backup is in progress and the computer might slow down. I get that warning but I notice no slowdown. When I got that warning with my 2007 iMac I sometimes did notice it.
My question seems to come down to, to what extent will the Fusion Drive add to all of the background activity that is slowing down my current system
If your asking about how the shuffling of data between SSD and HD that is done by the OS will impact your system the answer is it will be negligible. Remember the OS is doing this in the background when there are free CPU and Disk cycles available. It isn;t going to take from a user job to do this.
Now if you have the disk so bound up with all your backups that there are little free cycles for the OS to steal then that may affect the efficiency of the fusion drive but it won't add to the user load.
Having said that I doubt there is much you could do to the system short of running dd's continuously that would keep the fusion drive from doing its thing. Remember this is working at the block level. Files put on the SSD are not put there in their entirety. A file can (and most likely will) be split with parts of it on the SSD and parts on the HD. So there aren't huge data transfers going on between SSD and HD.
So I wouldn;t worry about the fusion drive adding to your already high disk load. But as everyone else here has written while backups are a good thing you can have to much of a good thing.
Hi, again Kenneth,
Every one here has a point about backups. You seem so obsessed with having constant backups and redundancy.
This is one reason your IMac is taking a performance hit.
No computer can run fast if it has to constantly access the computer's hard drive trying to backup data to another drive.
You're paranoid now because 10 years, ago, when you you almost lost your data,,you probably had zero backups and a poor backup plan, if any.
You do not need to backup constantly while you are working. That's why you have a save/ save as function on your Mac and OS X 10.8, I believe does automatic saves. Most companies that have an IT department or someone who is the general computer network administrator, in small companies, usually do daily backups at the end of the work day and then a complete weekly backup at the end of the work week. Either on a Fri. or over the weekend.
Without knowing what kind of work you do, why do you need to have 15/16 applications open and running constantly. You can't possibly be using every one of these applications every single day all day long.
Finding that hard to believe.
Your working habits are what is really slowing down the efficiency of yournMac.
No Mac will ever be fast enough when you have this much CPU, RAM and hard drive activity going on at once.
Multi-tasking is one thing, but you have major mega multi-tasking going on and the iMac just can't handle it all.
As far as the slow statups, OS X 10.7 and 10.8 are slower to boot up.
But your problem is you need to disable the Resume function in OS X 10.8 because, if you have a lot of applications still open at the end of your day, all of these applications are trying to reopen when you startup in the morning. That is why it is taking 10-15 minutes for your iMac just to boot up!