Hi, I have a software RAID 0 set which apperas as "Degraded" in Disk Utility (boot OS X is not on it). I canot find a way to rebuild the set as the "Update" botton is always greyed out regardless what i select in the window.
Can anybody help me?
TIA
Simon
Message was edited by: majortom67
iMac 27" - Core i7,
Mac OS X (10.6.2),
4Gbyte RAM - 1TByte HD - Ati 4850/512
Your picture shows RAID-1, not RAID-0. The set is "degraded" because there's no mirror partition. There's just one partition in the RAID set. The system is simply telling you that there's no mirroring going on.
That said, you also appear to be using two external hard disks for this purpose, apparently the idea being that they would be RAID-1 mirrors of each other. The problem is that both disks are USB disks. USB shares it's bandwidth across all devices and writes to devices will occur sequentially. By making a RAID set across the USB disks, you have the effective bandwidth to each disk and increase the latency. The practical upshot being that if the RAID is properly configured, the performance will be < 50% that of either drive individually (and the CPU usage to handle that much USB traffic and the mirroring will be pretty high too).
A better solution for RAID-1 is to purchase a dedicated enclosure. Such dual-drive RAID-1 enclosures don't cost too much, and they place the RAID-1 controller directly in the enclosure. From the standpoint of the OS, it appears as a single disk, and you get 100% the performance of the disks with minimal CPU overhead. A firewire enclosure is even better (performance-wise), if you can find a decent one.
I mean that USB/eSATA enclosures are; that USB is goes without saying; and that quad-interface is "jack of all, master of none." Some work, some are iffy; but native SATA controllers and those "consumer" cases with eSATA and FW/USB aren't built with each other in mind - found more commonly on your PC. And USB on PCs is also better. My PC has more channels and bus for USB.
An ExpressCard can add eSATA or FW800 and some are designed for low end two drive setups.
Some dual drive cases use RAID0 or 1 built in - as I said in my 1st reply above - with the intention of built-in protection. And RAID0 in such case is as much to have an expanded capacity as performance.
There are also NAS drives for backup, TimeMachine and more.
OK, my language was improper. It's a MIRRORED RAID.
But you solution is not good: I had it before into a WD FW800/400/USB2 box and when the electrical part failed I got all my data gone (WD replaced everything instead of taking my drives and puting them into another box - you miight argue that I should have a backup of that RAID-1. What do I have to do? RAID 0+1?). everytregardles there was a RAID1. Do you understand now why I prefer two boxes?
So lets get to the solution: can I remove the 3 RAID sets maintaining the datas on the disks (al least the ones in the good HD), repartition the bad one and rebuild my RAID sets? Or will the RAID removal destroy datas from all the partitions?
TIA
Simon
