Windows 7: RAID 1 issue

I have windows 7 ultimate setup with some mirrors made up of two logical drives that are 6TB. They are constantly resynching.

Should I assume that the disk that is not in sync would be unusable or would I still be able to use it to access the files if the other disk fails?
What I need to accomplish is a backup copy of the files on a disk that is written to each day to carry offsite. It would be best if the software could write to both locations at once but it does not support this.

Additionally, I am considering something like rsync instead if it could keep up with the changes.

Thanks

RAID1 isn't really meant to keep an internal and an external drive synced. If that's all that's needed, I'd just use SyncToy, which can even be scheduled, I believe.

I will look at that. I have been looking at a lot of options but they all seem to have problems with larger files according to posts I have seen. I will have to do some testing I guess.

By the way the drives are both external. Not that it really matters, I just need the files I write to go to two places.

How large of a file? Before I bought my WHS box, I used SyncToy to keep my data drive synced with an external USB drive, and some of the files were 7-8 GB in size.

They should not be much more than 8GB. The thing I am seeing is that it only copies the files. If something were able to make changes to files while the original was in use it would likely work good like rsync in Linux. The problem being file access issues and the need to recopying entire files that have changed causing it to be out if sync for quite a while. Lets say I wrote 1500GB and finished at 7:00 pm. It could take quite some time for it to catch up.

I am seeing about 60MB/sec write time but it still takes hours to copy in this way. That's why I am trying to use RAID mirroring.

The drives were 18TB before I broke it down to 6TB drives. Still seems unmanageable.

When you are talking about that much data, without the ability to shut them down for easy access and copying, you should consider storing a local backup on a server, and then having the server be backed up at night to either tape medium that can be carried out, or an online backup service. You'd still have the data stored off-site, but it could be done at a regular interval, without your interaction.

Yes, this basically seems impossible but my job in this is to have two copies of these files every day in case something happens. The servers are in a trailer on a remote location such as it would not be possible to upload. It is not even possible to copy the files from one drive to another sitting here on the server because it takes too long. A loss of one days files could be five weeks work and is not acceptable.

With the mirror it is possible in that the systems are turned off and the four disks making up one of the 6TB drives is removed and carried offsite each night and returned in the morning. After the 6TB mirror is full the copy can stay in town storage and the broken mirror can be used for reading while another 6TB mirror is used for writing.

Main problem being the mirror keeps resynching which has taken two days and is now at 96%. If it remains health then no problem.

The mirror has finished synching and I rebooted the system and its still healthy. Hope it stays good for now. I talked to the people about writing files to two paths and they said they had it working but not ready for release yet. Maybe the mirror will last until then. From what I have been seeing on the internet a lot of people have the same problem with the windows 7 software raid. I believe it must be a bug somewhere.

I saw some kernel power events in the logs so it appears it did not shut down properly triggering a rsync to be triggered.

Hi,

I see that your RAID has now re-sync'ed.

To answer your questions : with a RAID1, you should still be able to access the other disk, but the access time will be significantly slower. In your situation, with so much data...essentially not workable.

You sound like you have a significant dataset. Since you use 1.5TB drives, that means you have 8 x 1.5TB drives? Is that correct? Do these sit in a external enclosure connected by eSATA?

If you can't use a specific network solution (even a portable NAS), which really is the way to go with this amount of data, and if your motherboard supports it, you may want to consider a hardware RAID5 or even a RAID10. However, that means more disks. I have heard anectodal evidence that software RAID is far poorer in performance than a hardware RAID, but I have never tried a software RAID myself.

Regards,
Golden

Thanks for the answer.

What I have on hand at the moment is a couple of s24f infortrend units using fiber channel interface with 24 2TB disks each.

They were setup as 10 disk raid 5 18TB which is unmanageable and a second drive failure is likely when rebuild takes a week if its not on 24/7. I now have it setup as 4 2TB disk raid 5 at 6TB which rebuilds in 30 hours.

This is good as it is but having a daily offsite backup copy is not possible due to the time it takes to copy.

For some reason it does not appear possible to create a raid 1 out of two raid 5 drives on the infortrend so I am using windows raid 1 to build a copy on a raid 5 and those four disks are removed every evening.