ATA mirroring

[crabby117]

In the past, my coworker said he's been able to use a mobo's SATA RAID mirroring capabilities to mirror an existing drive. He took a primary hard drive, which already had the OS and data, and mirrored it without having to wipe out the drive.

Is this ability dependant on the raid controller or the drive type (ATA/SATA/SCSI)? I always thought the drives would have to be wiped out because the mirroring process creates overhead on the drive. I was hoping to get a PCI RAID card, and a second hard drive (identical to the first of course) to build a mirror configuration, but I don't want to wipe out my primary data drive. (I know I'd have to load the RAID controller drivers beforehand.) Can it be done?

 

[Freestone]

You would definitely lose data in a RAID 0 setup as the data would have to be striped across the drives, however RAID1 is mirroring, so it would depend on the controller used.

From the User's Guide for the Adaptec ATA RAID 1200A which states "Caution: If you proceed to create RAID, all the data stored in the hard disks will be lost. The exception is RAID 1 Duplication where data is copied from the Source disk to the Target disk."

So to be sure that you won't lose data, review the documentation for the controller you intend to use and see if it has similar RAID 1 capabilities.

 

[RDSKC]

this has been our experience as well, we set up servers for our customers using the Duplidisk raid case, which is Raid 1. Normally the programmers will get the box loaded the way they want it, and we go in after the fact and set up the mirroring process and we're good to go!

 

[jurgen36]

You are all correct up to a point. The Intel D875PBZ bord can actually convert a single Sata drive into a raid 0 or raid 1 drive, once you add another drive of course. I could not see how they do it and gave it a try. I installed a single 220 Gig Maxtor Sata drive and filled it up with Wxp and 164 Gbytes of data. I then added another identical drive and followed their instructions. I could use the machine during the conversion to raid 0, but the P3.2 HTEE cpu slowed down somewhat and the temperature went to 72 C. It is a slow process and took over night, however there was no data loss and the drive array now reads as 440 Gbytes. So it can be done but is rather slow. Raid 1 conversions are no problems at all. They just copy the drive across as a mirror image. The only trouble with raid 1 conversion is fingertrouble. You must know exactly what you are doing. Regards

Jurgen

 

[Freestone]

Thanks for taking the time to perform that test, Jurgen. I never thought striping could be possible without data loss. So it all comes down to knowing the capabilities of the controller, for all of its modes.

 

[bardsong]

Has anyone ever "converted" from RAID 1 on two drives to RAID 0 or no RAID? Just thinking ahead that if my two RAID 1 hds ever get full, that I could double the space by changing the RAID. Ideally I'd see two drive letters in Windows Explorer, be able to read/write from both and initially see identical file listings from the redundancy. Has anyone does this?

Thanks in advance!

 

[jurgen36]

: bardsong
That will be no problem at all. You just remove one drive and boot up in normal no raid mode. Both drives will have identical info on them. I have done this many times. However to convert it to raid 0 is not so easy. The intel D875PBZ bord can do it ok. I am not so sure about other bords. Regards

Jurgen

 

[bardsong]

Thanks, Freestone.

I think my mind is made up. I'm going with 1 160 Gb drive (free upgrade from 80 Gb) for now. I can always buy a 250 Gb external USB drive, extra HD and RAID card (that you mentioned--thanks!) to copy all data to the USB drive, add new HD, add new RAID card and configure to RAID 1 or 0 depending on amount of data I have then. When done, I'll delete the data from the USB drive and have a great working system. Sounds like some work, but it fits my situation pretty well.

Again thanks for your input, and any suggestions are welcome!