How do you know if a RAID 1 drive fails?

LeandrodaFL · Mar 8, 2013

Lets say I have a RAID 1 volume (2x drives). Its been said that if a drive fails, the other one continues operating normally with acess to all your data...so when this happen....HOW DO I KNOW THE FIRST DRIVE IS DEAD?

I mean, will Disk Utility Pop-up and warn me a drive has died, or will I never notice this..until the 2nd drive dies too and then I notice that the volume is no longer mounted on the finder.....wich by then would be too late....

jav6454 · Mar 8, 2013

Nothing will tell you "Hey, one of your disks broke!"

You have to run disk utility on the drive itself. On a PC, Intel's software RAID solution (and even hardware solutions) provides you with the health of the RAID array upon boot up.

On a Mac, not so much as you don't get BIOS class messages.

LeandrodaFL · Mar 8, 2013

jav6454 said:
Nothing will tell you "Hey, one of your disks broke!".

Great, so the broken RAID volume doesnt unmount till all drives are broken. What a terrible backup solution.

jav6454 · Mar 8, 2013

LeandrodaFL said:
Great, so the broken RAID volume doesnt unmount till all drives are broken. What a terrible backup solution.

Two drives in RAID is not a sure-thing back up solution. You need 4 drives to really have a respectable RAID backup solution. Also, a general check up every 6 months isn't really troublesome or bad.

sidewinder · Mar 8, 2013

RAID1, or any version of RAID, is not a backup system. It is for redundancy and higher availability.

Repeat, RAID1 is not a backup system. If you want backups, make backups....

S-

jav6454 · Mar 8, 2013

sidewinder said:
RAID1, or any version of RAID, is not a backup system. It is for redundancy and higher availability.

Repeat, RAID1 is not a backup system. If you want backups, make backups....

S-

True, but RAID provides an always available type backup.

sidewinder · Mar 8, 2013

jav6454 said:
True, but RAID provides an always available type backup.

No, it does not. RAID1 does not help if you accidentally delete a file. It's gone off the mirror as well.

RAID is not a backup system in any way, shape, or form. RAID1 is for redundancy and higher availability. "Redundancy" does not equal "backup".

S-

mannyo1221 · Mar 9, 2013

LeandrodaFL said:
Great, so the broken RAID volume doesnt unmount till all drives are broken. What a terrible backup solution.

Thats the whole point of it, if one drive fails the computer carries on running.

Raid 1 should not be viewed as a backup, its not and that is not its intended purpose. The intended purpose is to avoid data loss and downtime in the event of a drive failure. In the corporate world, Raid 1 is very common for operating system drives on server hardware so that they continue running if a drive fails.

A windows home computer BIOS should alert you when you reboot if one of the raid 1 drives has failed, failing that your motherboard manufacturer usually has additional software that can be installed to monitor the raid drives.

For Mac, I don't know. There must be some way to identify a failed drive, doesn't disk utility show you the drive status?.

justperry · Mar 9, 2013

mannyo1221 said:
Thats the whole point of it, if one drive fails the computer carries on running.

Raid 1 should not be viewed as a backup, its not and that is not its intended purpose. The intended purpose is to avoid data loss and downtime in the event of a drive failure. In the corporate world, Raid 1 is very common for operating system drives on server hardware so that they continue running if a drive fails.

A windows home computer BIOS should alert you when you reboot if one of the raid 1 drives has failed, failing that your motherboard manufacturer usually has additional software that can be installed to monitor the raid drives.

For Mac, I don't know. There must be some way to identify a failed drive, doesn't disk utility show you the drive status?.

There are ways, contrary what people say above, plenty of Apps monitoring the state of the drive, most of them install a deamon to monitor, example is Diskwarrior.(See screenshot)

Oh, and if this does not work on RAID then there's many manufacturers which include software to do just that.

LeandrodaFL · Mar 9, 2013

sidewinder said:
RAID1 does not help if you accidentally delete a file. It's gone off the mirror as well. -

Thats exactly what a I want, if I delete a file, I want it deleted on the backup as well, I want 100% same drive status.

And RAID 1 does provide a sort of backup solutuion nevertheless, and it was very used 10 years ago when external drives were not common and backup software werent that great.

Lets be honest, nobody is retarded enough to delete a file and empty the trash on accident. And even so, it can still be recovered.

And even more so in my case, I want to RAID 1 2 external drives to keep as a download hdd with temporary stuff only, I do backup my internal drive with Time Machine.

I was only sad that I wanted some kind of warning if a drive fails on the RAID 1 so I can replace it...

benwiggy · Mar 9, 2013

LeandrodaFL said:
Lets be honest, nobody is retarded enough to delete a file and empty the trash on accident.

Thousands of posts on this forum would disagree with you. There are plenty of people who claim to have deleted all sorts of files and not found them in the Trash. And plenty of people without backups, too.

LeandrodaFL said:
And RAID 1 does provide a sort of backup solutuion nevertheless

I'm going to have to join all the people telling you that it does not. RAID 1 means if a drive fails you can keep working while you fix it. It's designed for mission critical stuff where downtime is not an option. It is distinct from a backup for the very reason given: it does not provide a way to recover corrupted, overwritten or deleted files, and it provides no historical snapshots.

LeandrodaFL said:
I want to RAID 1 2 external drives to keep as a download hdd with temporary stuff only

If it's temporary stuff, why do you feel the need to create a RAID?

LeandrodaFL · Mar 9, 2013

benwiggy said:
If it's temporary stuff, why do you feel the need to create a RAID?

Cause if a drive fails, data can still be recovered...I want to be able to sleep at night

marzer · Mar 9, 2013

LeandrodaFL said:
Cause if a drive fails, data can still be recovered...I want to be able to sleep at night

You lose sleep over the volatility of your temporary data storage device?

For truly temp data storage, IMO, RAID 0 is the more effective use of storage media. Maximize your storage capacity and possibly device performance.

How are you creating the RAID? I've used the RAID software in OS X on and off over the years, its pretty unreliable. Especially with USB drives. If you are using a third party solution, ex. Softraid or a hardware RAID solution, those will come with failure monitoring, reporting and recovery.

LeandrodaFL · Mar 9, 2013

marzer said:
How are you creating the RAID?

Im gonna RAID 2x Firewire drives in daisy chain.

blueroom · Mar 9, 2013

Remember, RAID is not a backup.

marzer · Mar 10, 2013

LeandrodaFL said:
Im gonna RAID 2x Firewire drives in daisy chain.

Using The RAID built into OS X? You may want to consider using a third party solution. As pointed out, its not very fault tolerant.

LeandrodaFL · Mar 10, 2013

marzer said:
Using The RAID built into OS X? You may want to consider using a third party solution. As pointed out, its not very fault tolerant.

Thanks for the advice, but Im gonna go with disk utility and see what happens

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