Why has my Lacie 5big 20TB thunderbolt hard drive speeds dropped to half suddenly?

[Essami]

Hi,

Today I started editing with Premiere Pro CC and noticed the playback was choppy and I had to pause and play to get the image on the preview screen even at half quality. I ran the diskspeed utility test and it shows my 20TB thunderbolt Lacie hard drive read speeds at almost half of what they used to be.

Write speed used to be 756MB/s and now shows 502 MB/s.
Read speed was 539 MB/s and now shows 297MB/s.

I'm on an iMac and I've tried to think if I have installed some programs that might be the cause? The external Lacie still has 11TB free out of the 20TB available. It's in raid 5 configuration and in that regard I haven't changed anything that I know of.

Any advice or hints what might be going on?

Best,

Sami

 

[nyvz]

When you say what it used to be, do you mean when the drive was empty or do you mean recently? Hard drives all slow down as they get full and start reading/writing more from the inner tracks which have lower linear velocity given the constant platter rotation speed. A nearly full drive will tend to run at about half the speed it was when it was full, assuming no interface bottlenecks and no fragmentation. Perhaps try connecting it to another computer to see if it may be a limitation of your iMac?

Does LaCie have a utility that can diagnose and/or rebuild the array? That might be worth trying, as well as any firmware updates.

 

[Essami]

Yes, the first time I tested when the drive was empty and the second time was just now. Six months since purchase.

But it seems that after shutting the computer and external hard drive for about an hour the speeds are back... Just tested again and it says Write speed 560 MB/s and read speed 540 MB/s. I did try to restart before but could it have been overheating or something...

I should point Im using a 5.5 meter optical thunderbolt cable and have the Lacie in another room from my iMac.