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Xevious
05-06-09, 03:09 AM
I never noticed this until having multiple drives hooked up to the machine but my dads nforce 750i based machine is showing some horrid write speeds on it. I was moving him to a raid1 configuration using the nv fakeraid and noticed under linux dd'ing the data was incredibly slow. It was fast earlier so I tried re-creating the raid array and it was quick again (DD averaged 100 MB/sec for 1 TB of data). Well after I got his system back up and running on windows the write speeds are being slow as hell again.

We are talking 2-5 megabytes/sec slow. This causes windows to show generally slow behavior hdtune shows horrid write speeds on the fs test.

This is when using 2x1.5 TB seagate drives (running a new CC1H firmware) in raid1. Anyone know what might be causing this? my next test is going to be adding a jumper limiting the drives to SATA150 to see if that helps things at all.

Read speed is great as hdtach/hdtune both show around 120 MB/sec at the beggining of the array.

john19055
05-08-09, 12:23 AM
You could gain speed if you set up a Raid-0 ,but you would loose the safety if a harddrive failed.I always hook mine up in a Raid-0 so I get the extra speed. I have not ever had a harddrive go bad ,knock on wood.Have you tried just running one harddrive and not mess with the raid.

Xevious
05-08-09, 01:10 AM
You could gain speed if you set up a Raid-0 ,but you would loose the safety if a harddrive failed.I always hook mine up in a Raid-0 so I get the extra speed. I have not ever had a harddrive go bad ,knock on wood.Have you tried just running one harddrive and not mess with the raid.

Never had a hard-drive go bad? You have been lucky then! The whole reason for the raid was for redundancy not speed. I can't believe someone would recommend raid0, LOL!

I actually procrastinated on moving my dad to raid1 the week before and sadly his hard-drive took a dump that week. Over 2000 re-allocated sectors and the drive would keep turning off when a certain part of the drive was read. dd_rhelp, dd_rescue, SATA -> USB adapter, and many hours of unplugging and plugging the drives power back in later I was able to recover all but around 400kb of data off the drive.

Anyway I figured out what the issue was. Apparently speeds are absolutely crap unless you have write-back enabled in the disk properties in windows. This wouldn't surprise me on parity raids but I don't see why raid1 would suffer such huge write issues without write-back which can cause corruption if the system crashes or loses power. It kind of pisses me off that this has to be enabled.


Before write-back:
http://box.houkouonchi.jp/slowdisk.png

After write-back:
http://box.houkouonchi.jp/fastdisk.png