System slow when RAID 1 is set

harissahlan

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Sep 10, 2013
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Hi,

I have 2 HDDs, an SSD, and an optical drive. I am having problem when setting RAID 1 with my HDDs.

At first, I set up RAID 1 for the HDDs, but then I noticed the system became really slow and the HDD LED kept turning on. I tried to use other power cables for the second HDD, but it was still the same. Even when I unplugged the power (PSU) cable from the SSD and optical drive, and power the HDDs with separate power cable, it was still the same.

Later, I undid the RAID so the HDDs ran separately. The computer ran normally and the LED didn't always on. However, when I open Computer in Windows, I didn't see my second HDD there. When I checked the Disk Management, the missing HDD was marked as 'Offline'. So, I set it back online there and the second HDD was detected and ran normally. I had no problem with HDDs and other devices then. At this time, the HDDs were powered by the same cable from power supply.

Later I tried to set up RAID 1 again using Intel RST. The set up ran without error, but, again, the system became slow and the HDD LED was always on. What could be the problem?

Thanks in advance.

Regards,


Haris
 

Joshua Carter

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Aug 30, 2013
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Raid 1 is going to be slow while it builds because Raid 1 is a mirrored set. The reason it is slow is because its building the mirror. Once it is finished building the mirror your speed will go back to normal. If you're looking for a speed enhancement over normal, you want to be using raid 0, not 1. The drawback with 0 though, is that if one of the 2 drives fail that volume is useless because the data is split equally between all of the drives in the Raid.
 

Joshua Carter

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Aug 30, 2013
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Raid 1 is going to be slow while it builds because Raid 1 is a mirrored set. The reason it is slow is because its building the mirror. Once it is finished building the mirror your speed will go back to normal. If you're looking for a speed enhancement over normal, you want to be using raid 0, not 1. The drawback with 0 though, is that if one of the 2 drives fail that volume is useless because the data is split equally between all of the drives in the Raid.
 
If one of your HDD's in your RAID1 array is faulty it will jam everything up

RAID1 is no safer then RAID0 if you dont back your data up - RAID1 does not protect against deletion, corruption or virus's etc

If the arrays is just rebuilding leave your rig on overnight to complete it
 

Jack Black

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Mar 23, 2014
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I have had the same issue as the OP. It was not due to the RAID1 rebuilding. Rebuilding will slow the array down, but not nearly as much as the problem I am experiencing. I am using 5 drives on my Intel Rapid Storage Technology controller, which is built into the MB. 3 x 10,000rpm Seagate Velociraptors as a single RAID0. This array works great. 300MB/s Read & 160MB/s Write speed.

The problem is with the two WD Black drives setup as RAID1. Particularly when copying many small files it can take an inordinate amount of time. For instance, when I copy a particular folder to or from the RAID0 drive or any other drive I get 60-80MB/s transfer and it takes about 2-3 seconds. When I copy the same folder "FROM" the RAID1 it will vary between 200KB/s to 6MB/sec. It can take as long as 30-40 seconds. Reading from the RAID 1 array is the main problem. Writing to it seems to be normal at about 60-80MB/s. I am using the Intel RST Driver Version 12.9.0.1001. I have also tried version 12.8.0.1016.

I have tried older versions of the Intel driver and the problem persists. It occurs on both Windows 7 and Windows 8/8.1. I have yet to try Ubuntu on this particular PC.
 
Ummm old thread

Mechanical drives = slow, raid 1 does NOT equal MORE performance on cheap/integrated raid devices

Seagate doesnt make the raptors WD does

Your pointing out limitations of a mechanical drive not a RAID setup, and your not accounting for disk caching (background transfers etc)
 

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