When I try to copy big file/files >= 10 GB, my whole system slows down. Applications take long time to open. Even I can't type smoothly, video player starts frame drop. But everything goes normal immediately after finish the copy/move operation. I copy from one Ext4 partition to another Ext4 partition in same HDD. I also tried NTFS to Ext4 and vice versa. My system is up to date.

System info:

CPU: Corei7
Ubuntu 14.04 64bit 

HDD info:


 Model=WDC WD10JPVX-80JC3T0, FwRev=01.01A01, SerialNo=WD-WX11AA3E8770
 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
 RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=0
 BuffType=unknown, BuffSize=8192kB, MaxMultSect=16, MultSect=off
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=1953525168
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio3 pio4 
 DMA modes:  mdma0 mdma1 mdma2 
 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 
 AdvancedPM=yes: unknown setting WriteCache=enabled
 Drive conforms to: Unspecified:  ATA/ATAPI-1,2,3,4,5,6,7

 * signifies the current active mode

Same things happen when try to copy from USB drive. I'm sure it's bug but I'm not sure which package is causing this problem.

  • Just one point which was not clear to me. Is "NTFS to Ext4 and vice versa" slow too? – user.dz Sep 9 '15 at 7:20

The answer is obvious. You HDD has limited read/write speed.

When it is busy with copying files, it takes more time to read files from disk. That is why applications start slower and you have slowdowns and drops when watching video.

It is normal.

If it is really important to watch a video while copying, you can set a higher priority to your media player, e.g. in System Monitor.

  • 1
    But as I know HDD has UDMA features. And I also checked my cpu status it's quite normal. There is no process eating cpu or ram. So why system will slow down in that scale?? I am talking about really slow. – shantanu Jun 7 '15 at 19:57
  • It has nothing to do with CPU or RAM. It is bus and HDD throughput. – Pilot6 Jun 7 '15 at 19:58
  • 1
    And the system is not slow itself. Only disk operations slowdown. – Pilot6 Jun 7 '15 at 19:59
  • Is there any option to balance these?? I don't need highest speed of copy. – shantanu Jun 7 '15 at 20:02
  • You can try this or other answers there. – Pilot6 Jun 7 '15 at 20:08

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