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Question

2-drive RAID 1 crashes when copying files

May 17, 2016 8:27AM PDT

I had a two disk RAID 1 that was acting odd. I thought it had died, and was advised it was by the manufacturer's tech support. I backed up the data and ordered a new enclosure from a different vendor. I loaded formatted drives to the new enclosure. Whenever I copy files to it, the raid crashes and disconnects.

In single mode, where both the drives in the enclosure show up as individual drives, things copy just fine. So I thought the enclosure had bad RAID hardware parts. To verify, I loaded two different drives into the RAID, and things seem to be copying just fine.

What is happening? Is it possible that one of the original drives is damaged just enough to make it perform poorly, making the RAID crash? I've been trying to eliminate as many variables as possible. I know that the issue is not corrupt files since there have been crashes as RAID with multiple different copy sources, while successful copies from the same sources as a generic transfer. I have run a disk utility first aid on all the individual drives and all verified as OK. Since this is connected to a Mac, support suggested I install SMART drivers, which I did with no change.

Any help would be greatly appreciated.

Cheers

Discussion is locked

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Answer
Not much new going on here.
May 17, 2016 8:46AM PDT

All drives today still need backup copies. If you left your backup to the day when something failed then you are going to possibly lose some files.

Since you are on a Apple computer my other ideas on copy software may not apply so your next move may be to get an estimate from Drivesavers.com

RAID is not backup. I've seen folk try to use RAID 1 as backup and it fails leaving them in a fit. Same story here. Don't rely on a single system.

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Drives read as fine
May 17, 2016 8:59AM PDT

I was able to back up the files from the RAID, and the drives read as OK with I run First Aid from Disk Utility. (FYI - I don't use RAID 1 as a backup, I have a separate drive for that, but as a way to prevent from a drive going bad wiping away data). So data recovery is not what I'm needing.

I'm struggling with why the enclosure is not allowing me to copy files. To summarize:

• Original drives in new enclosure, files copied using RAID1 - Fail
• Different drives in new enclosure, files copied using RAID1 - Pass
• Original drives in new enclosure, files copied using generic, single mount - Pass

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I've seen that.
May 17, 2016 9:37AM PDT

And the drive still fails. So we replace them. This can royally upset folk or clients that want a drive to be good because tests pass.

Reality is that you will encounter drives that pass tests but fail otherwise. These mystery drives are best tossed in the recycle bin or given away to your enemies.

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:-(
May 17, 2016 9:39AM PDT

Is there a way to tell which of the two is the questionable one, if both pass tests?

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Maybe with extended testing.
May 18, 2016 10:34AM PDT

You can try a zero fill with say DBAN and time how long it takes. In the past I've used this to sniff out a bum drive. It's not fool proof but has found Waldo too many times.

You should also look into the SMART report. The drive with the worst report is the suspect.