Wraith44
03-12-2009, 09:39 AM
I built a Matrix RAID 0 and RAID 1 array, using 2 disks, a few weeks ago. Unfortunately, one of the drives failed after only a week, so I had to RMA it back to Newegg for a replacement. After I installed the new drive, I booted into Windows (off of the good RAID 1 partition) and, using the Matrix management console, I added the new disk to the array and started the RAID 0 rebuild process. While it was rebuilding, I recreated the RAID 1 array (which I'd already deleted) and then quick formatted it with NTFS.
After the rebuild had completed, I started restoring my backed up data to the RAID 0 array, but I immediately noticed that it was running extremely slow. My first thought was that something else was accessing the hard drive and slowing the transfer rate. However, after killing all non-system programs and services and making sure that nothing was hitting either drive through Filemon, there was still no change in performance. I then ran HD Tune Pro and noticed that read tests to both RAID 0 and 1 arrays were slow with massive spikes in speed near the start of both partitions (going from 180MB/s to 2MB/s).
After trying everything I could think of, it dawned on me that it might have had something to do with creating the RAID 0 array while the RAID 1 array was being rebuilt. Now, when I did this, I was going on the assumption that the RAID 1 array should have blocked off the portion of the new drive that it needed to create the mirror. However, it appears that that might not be the case.
So, the question is, when you rebuild a RAID 1 array, does it just rebuild the data sequentially and not block off/assign the portion of the disk that it needs right away? Should I let the RAID 1 array complete the rebuild first and then create the RAID 1 array? My thought is that the RAID 0 array must be just grabbing the first available space on the drive, and if it's not assigned to the RAID 1 array yet, it's going to cause massive fragmentation, which is why I was seeing the huge spike in performance. Can anyone confirm or deny this? What is the correct way to rebuild both arrays while retaining the RAID 1 array on the original disk?
After the rebuild had completed, I started restoring my backed up data to the RAID 0 array, but I immediately noticed that it was running extremely slow. My first thought was that something else was accessing the hard drive and slowing the transfer rate. However, after killing all non-system programs and services and making sure that nothing was hitting either drive through Filemon, there was still no change in performance. I then ran HD Tune Pro and noticed that read tests to both RAID 0 and 1 arrays were slow with massive spikes in speed near the start of both partitions (going from 180MB/s to 2MB/s).
After trying everything I could think of, it dawned on me that it might have had something to do with creating the RAID 0 array while the RAID 1 array was being rebuilt. Now, when I did this, I was going on the assumption that the RAID 1 array should have blocked off the portion of the new drive that it needed to create the mirror. However, it appears that that might not be the case.
So, the question is, when you rebuild a RAID 1 array, does it just rebuild the data sequentially and not block off/assign the portion of the disk that it needs right away? Should I let the RAID 1 array complete the rebuild first and then create the RAID 1 array? My thought is that the RAID 0 array must be just grabbing the first available space on the drive, and if it's not assigned to the RAID 1 array yet, it's going to cause massive fragmentation, which is why I was seeing the huge spike in performance. Can anyone confirm or deny this? What is the correct way to rebuild both arrays while retaining the RAID 1 array on the original disk?