Guid Partition or Apple Partition?

GUID since it's an Intel iMac.

RAID basically gives you a redundant array of mirroring drives if setup correctly. It is great in a server setup as it simplifies backing up to be very quick. The downside, if you don't know what you are doing is you can quickly lose track of the space you are managing. I prefer Just a Bunch Of Disks (JBOD) because then I know what is going where and when. I would get on the phone with Iomega to ensure your drive is optimized for the use you desire and redundancy you desire from the get go. Because once set wrong, you may have to lose everything before it can change again.

Message was edited by: a brody

I'll go for: do not daisy chain.

Take a look at OWC's RAID5 4-drive enclosure with quad-interface.

dakota73 wrote:
thanks. now finally, do they all need to be GUID or is mixing with Apple Partition ok?

Why? GUID is the newer formatting standard. Apple Partition is old school. What do you think you are going to gain with that?


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Allan


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For *data drives,* it doesn't matter which partition map you use, and you can mix & match drives with GUID and APM partition schemes in the same FW daisy-chain or USB hub. However, I would suggest that if you have an Intel Mac and are installing new drives, I would go with GUID partition maps on all, for consistency.

For *Time Machine* drives on an Intel system, use the GUID partition map.

Of some interest is that Intel Macs can actually boot from both GUID and APM drives provided OS X is already installed on the drive; however on an Intel Mac, the OS X installer will only allow you to install OS X on a GUID drive.

PPC Macs can only boot from an APM drive. The only other limitation for APM is that the maximum allowed disk size is 2TB (1x10 ⁹ bytes) compared to GUID which can theoretically handle up to 9ZB (1x10x ²¹) byte drive size.

Regarding your intended uses, here's what I suggest:

1 2TB FW800 drive as your main data drive (your working drive)
1 xTB FW800 or USB2 drive for Time Machine (if you really want to use TM; just don't rely on TM as your primary image backup disk)
1 2TB FW800 drive as your primary backup drive
1 xTB FW800 drive as your secondary backup drive (some day you will bless your soul that you had the sense to have a second backup drive with a copy of everything that is on your primary backup drive)

The backup drives should only be connected when you are doing a backup or restore operation. Otherwise they should be unmounted, disconnected & powered off. It is even better if your secondary (or even tertiary) backup drive is kept offsite.

The reason for using all FW800 drives is that if you daisychain a FW400 drive to a FW800 port or FW800 drive it will slow down the entire FW bus to FW400 speeds, thereby doubling all your i/o times. And copying from an external FW800 drive to an external USB drive will be slower than if both drives are daisychained via FW800.

I have extensive libraries of images & video files; this is the setup I finally settled on after years of trial & error and it has served me well. I would not recommend RAID for image storage. If you are doing mid-to-high end video editing & processing then RAID may be of interest.

The biggest downside I see to TM is that in the case of a total system failure recovery from TM while possible takes longer to accomplish. That is one of the reasons why in addition to TM I also do periodic clones of my system disk with SuperDuper.

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Allan


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Corrections to two small typos in the formulas above:
2TB ( 2x10 ⁹)
9ZB ( 9x10 ²¹)

What I wrote in my previous post were the definitions of 1TB and 1ZB.

TM is a form of backup, but it is always online and it is not for archival purposes. It runs on a fixed schedule and will back up every modification you make to any folder or file. With image files it will chew up time and hard drive space faster than you can imagine. And as the drive fills and your backups age, TM prioritizes them lower & lower until it gets to the point that it drops (erases) the oldest backups.

A true backup should be under your full control. And the backup drive should not normally be online, as that exposes your backup to system, software and power threats which happen much more frequently than drive hardware failures.

I have used the Finder, CarbonCopyCloner, SuperDuper, Intego Backup Assistant and EMC Retrospect at one time or another. All work fine but you may find some of them more to your liking than others. I mostly use CCC and the Finder.

http://eshop.macsales.com/shop/hard-drives/RAID/Desktop/

GPT supports systems with EFI; improves on volume and partition integrity, supports 3TB and above. Is needed for TimeMachine and to install Mac OS on Intel (and while it may be possible, or was, consider it a must for booting also).