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Does a software raid on MacBook Air 11 w/Mac OSX Lion 10.7 impact performance?

I have a MacBook Air 11 1.8 Core i7 running Lion 10.7.2 connected to the Apple Thunderbolt Display which is in turn connected to a FW800 2 TB G-Drive which is connected to another 2 TB G-Drive via FW800. I have set the 2 drives up in a software RAID (block size 32) using Disk Utility. I have so far only created the iPhoto database on the RAID. I am experiencing the following issues:

1) When importing a large amount of photos the process often pauses for 5 seconds or so and then resumes.
2) Several times towards the end of an import the RAID disconnected from the system and the process stopped.
3) I often get the spinning beach ball, sometimes for quite a while when trying to start new processes, such as a copy or launching another app when the copying is happening.

Is this typical of Apple software RAID? Is there a problem in terms of the equipment I am using or how I have set it up? Is the MacBook Air not up to the task?

I have over 300gb of photos that I want to secure. I planned to use this RAID and then also use a Time Machine backup. But if this setup for the MacBook Air is not workable, I need a different solution, so please recommend.

Thanks in advance.
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Cyrill ReiserIT Director
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Commented:
Hey,

I'm not sure if I understand correctly how you connected the 2 FW800 drives.

You say that the MacBook air is connected to the Display using the Thunderbolt interface. Then you connected a Hard Drive to the FW800 port on the display. Then you connected the second Hard Drive to the FW800 port of the first Hard Drive. Is that correct?

Author

Commented:
Yes CyrRei88, that is correct.

Since my posting I have tried using SoftRAID 4.07 as well and just the Certify process seems to be taking an inordinately long time. With both drives at the same time the estimate was 82 hours. I stopped one drive and the estimate for the other is 55 hours. Not sure if that info helps at all.
Cyrill ReiserIT Director
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Commented:
Ok. You said you stopped one drive. Just to clarify, did you disconnect the second Hard Drive from the first Hard Drive? or did you just turn it off?

If you haven't already tried this, do the following:


1. Disconnect the first hard drive from the second hard drive.
2. Disconnect the first hard drive from the monitor.
3. Connect 1 of the hard drives to the monitor via FW800
4. I assume there is not data on the disks yet, so delete any RAID configurations
5. Format the drive using the Mac OS Extened File System
6. Now try to copy a large file or folder onto that disk.

Let me know if it is still slow.

On a side note. The 55 hours estimate might drop to a lower number after a couple of minutes. How long did you leave the drives connected when it said 55 hours?

Author

Commented:
I left it for about an hour when it was both drives and it was 82 hours. I then stopped one and it dropped to 50. I then stopped that and started the other drive (the first drive in the chain) and left it for about 20-30 minutes and it stayed at 55.

I will try connecting just one drive and see how that works, but I am not onsite now.
Cyrill ReiserIT Director
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Commented:
Ok, let me know how it work.

You shouldn't connect both drives together like that anyway, because the FIREWIRE bus has a limited amount of bandwidth available. Once you connect 2 drives to the same bus and run them at the same time, your bandwidth will be split in half between these 2 drives.

Author

Commented:
So would I be better off with 2 USB drives running off 2 of the 3 USB ports? (They all end up using the same Thunderbolt connection to the Air of course.)

Are these my options?
1) Get an external 2 drive RAID hardware setup (Western Digital or G-RAID)
2) Connect 2 USB Drives as stated above and software raid them
3) Connect 1 FW800 drive and 1 USB drive and use SuperDuper (or alternative) to do images nightly?

Which do you recommend or is there something else?
IT Director
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Commented:
Option 1

This would be ideal, since the controller on the G-RAID would take care of the whole RAID configuration. This would free up system resources on your MacBook. Also Hardware RAID configurations (in my option) are less likely to produce errors that software RAIDS.

Option 2

This is a possibility but you would run into the same problems as with the Firewire, since the USB ports most likely run on the same bus (unless apple provided a separate chip for each port, which is highly unlikely). Therefore you would have to split the bandwidth between the 2 drives.

Option 3
This might also be an option.


You have to try out and see what works best for you. Technically all options above should be possible, but I like Option 1 the best.

Oh yeah, I never asked, but you are talking about a RAID1? correct?

If I were you I would try it out with one hard disk first, because if that is really slow too, then there might be something else wrong with your setup.

Author

Commented:
Yes RAID 1. Thanks for the advice. I will try what you suggest and report back.

Author

Commented:
I connected just one drive and Partitioned it and then Zeroed out the drive and it worked. Port seemed fine. I bought a WD My Book Studio and changed it to RAID 1. We will see if that works better.

Thanks for the help.
Cyrill ReiserIT Director
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Commented:
Ok, let me know if you need more help.

Author

Commented:
Great timing. I am actually onsite and the solution with the external RAID 1 is working well.  I used the WD software to switch it to RAID 1 on a Snow Leopard machine and then zeroed out the drive. I have now transferred over 150GB to it on the Lion machine it will be permanently attached to and all seems good.

Here is what I learned:

1) I don't trust the Disk Utility software RAID
2) I recommend a Time Machine backup in addition to the RAID as I hear horror stories about all of these RAID solutions. (maybe even an additional offsite backup if your data is especially critical.
3) CyrRei88's explains the options well.

THANKS CyrRei88!
Cyrill ReiserIT Director
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Commented:
Glad to hear that it is working now.

You're very welcome.

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