4

Can any one explain me this ? I re-install BlackMagic but it ain't change a thing.

I'm running 10.9.3 and there is only one partition on the SSD.

enter image description here

With the terminal :

MBP-Thomas in ~
○ → dd if=/dev/zero bs=1024k of=tstfile count=1024
1024+0 records in
1024+0 records out
1073741824 bytes transferred in 35.587628 secs (30171773 bytes/sec)

 MBP-Thomas in ~
○ → dd if=tstfile  of=/dev/zero 
2097152+0 records in
2097152+0 records out
1073741824 bytes transferred in 11.061699 secs (97068437 bytes/sec)

 MBP-Thomas in ~
○ → cd /

 MBP-Thomas in /
○ → sudo dd if=/dev/zero bs=1024k of=tstfile count=1024
Password:
1024+0 records in
1024+0 records out
1073741824 bytes transferred in 33.653468 secs (31905830 bytes/sec)

 MBP-Thomas in /
○ → dd if=tstfile  of=/dev/zero 
2097152+0 records in
2097152+0 records out
1073741824 bytes transferred in 11.582934 secs (92700332 bytes/sec)

Which is also pretty bad...

Result of iotop :

MBP-Thomas in ~
○ → sudo iotop -C 5 12
Password:
Tracing... Please wait.
2014 May 29 12:07:16,  load: 1.38,  disk_r:      4 KB,  disk_w:   9124 KB

  UID    PID   PPID CMD              DEVICE  MAJ MIN D            BYTES
  501    284    277 cfprefsd         ??        1   2 R             4096
  501    284    277 cfprefsd         ??        1   2 W            16384
  501   3905     46 lssave           ??        1   2 W          9326592

2014 May 29 12:07:21,  load: 1.43,  disk_r:      0 KB,  disk_w:      0 KB

  UID    PID   PPID CMD              DEVICE  MAJ MIN D            BYTES

2014 May 29 12:07:26,  load: 1.40,  disk_r:     40 KB,  disk_w:   1960 KB

  UID    PID   PPID CMD              DEVICE  MAJ MIN D            BYTES
    0      1      0 launchd          ??        1   2 R            40960
    0      1      0 launchd          ??        1   5 W            40960
    0      0      0                  ??        1   5              74752
    0      0      0 kernel_task      ??        1   2 W           888832
    0      1      0 launchd          ??        1   2 W          1077248
    0      0      0                  ??        1   2            1200128

2014 May 29 12:07:31,  load: 1.36,  disk_r:      0 KB,  disk_w:     12 KB

  UID    PID   PPID CMD              DEVICE  MAJ MIN D            BYTES
  501    352    296 node-webkit      ??        1   2 W            12288

2014 May 29 12:07:36,  load: 1.33,  disk_r:      0 KB,  disk_w:      0 KB

  UID    PID   PPID CMD              DEVICE  MAJ MIN D            BYTES

2014 May 29 12:07:41,  load: 1.31,  disk_r:      0 KB,  disk_w:      0 KB

Update :

Ok. Now it says that writing speed is 27.4MB/s (27379034 bytes/sec) and reading speed is 4.45GB/s (4499797299 bytes/sec)

WTF ?

  • How much free space is there in the disk? Are you running other tasks when you do the test? – xpereta Oct 21 '13 at 10:11
  • @xpereta 1/3 free space, cpu used about 10% during tests – Thomas Ayoub Oct 21 '13 at 11:27
  • Does this happen to be an encrypted disk? – wrossmck May 29 '14 at 11:03
  • @wrossmck no encryption – Thomas Ayoub May 29 '14 at 13:56
  • I'm running an 840 Pro in a late 2009 iMac getting 250MB/s on read/write. The drive might be a lemon. If possible, try it in another computer. – Joseph Jun 4 '14 at 15:20
1

I have also experienced slow performance on an SSD and it was due to other active processes writing to the disk continously.

Have a look at question on superuser on how to monitor OSX disk activity: https://superuser.com/questions/89266/whats-causing-all-the-disk-activity-on-os-x

Basically run this either this command form Terminal:

iotop -C 5 12

or this other:

fs_usage

To locate any process that is writing to the disk continously.

Another thing to try is booting from a clean install of OSX on an external USB disk, and the benchmark the internal SSD.

I would also determine if the SDD is running the latest Samsung firmware. You can download the latest version from this Samsung support page: http://www.samsung.com/global/business/semiconductor/samsungssd/downloads.html

Beware that it is recommended to have a backup of the data before attempting to update the firmware.

  • Nothing anormal on fs_usage, see edited post for iotop – Thomas Ayoub May 29 '14 at 10:09
  • Another thing to try is booting from a clean install of OSX on an external USB disk. – xpereta Jun 4 '14 at 13:14
  • Same poor performances. But the system is not slow. It don't understand – Thomas Ayoub Jun 4 '14 at 14:29
0

Try running this command in terminal and let me know about the results

time dd if=/dev/zero bs=1024k of=tstfile count=1024
  • 1073741824 bytes transferred in 25.102759 secs (42773857 bytes/sec) which confirm the blackmagic test – Thomas Ayoub Oct 21 '13 at 11:26
  • Do you have Trim enabled ? Check here davidalison.com/2013/05/… – Patryk Oct 21 '13 at 12:18
  • Nop, it is disabled – Thomas Ayoub Oct 21 '13 at 12:24
  • Try to enable it and reboot the system. Also check Link Speed for SATA category in System Report window. Also read here for further info reviews.cnet.com/8301-13727_7-20052922-263.html – Patryk Oct 21 '13 at 12:31
  • Well it used to be 150MB/s on writing and 250MB/s on reading so it's not coming from the Link Speed – Thomas Ayoub Oct 21 '13 at 12:37

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