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iMac 27 core i7 two ssd slow speed

Can anyone help, please:


After installing two SSD on my 27' iMac I've tried Blackmagic disk speed test but it only shows 10 bmps or so. Simple copying of a 1 gb file from one folder to another also doesn't seem to be fast. I'v enabled TRIM but it hasn't changed anything...


Here's how I set it up step by step:


I've installed two SSD on my iMac (27-inch, Mid 2011, core i5)

At first I installed Crucial M500 240 Gb under DVD-Rom and was using it with my HDD as Fusion Drive.

Later I put Crucial MX100 512 Gb instead of HDD


I've set them up as RAID overall 750 gb or so.

Formatted and clean installed last Yosemite 10.10.2

Then I've discovered that my hard drive FAN is running at full speed - I've installed SSD Fan Control which is doing good - FAN is ok now.


I've also enabled trim via terminal as it shown here https://gist.github.com/return1/4058659/


When I'm checking SATA in system report it shows this


Intel 6 Series Chipset:


Vendor: Intel

Product: 6 Series Chipset

Link Speed: 6 Gigabit

Negotiated Link Speed: 6 Gigabit

Physical Interconnect: SATA

Description: AHCI Version 1.30 Supported



Capacity: 512,11 GB (512*110*190*592 bytes)

Model: Crucial_CT512MX100SSD1

Revision: MU01

Serial Number: 14440DA23C3B

Native Command Queuing: Yes

Queue Depth: 32

Removable Media: No

Detachable Drive: No

BSD Name: disk0

Medium Type: Solid State

TRIM Support: Yes

Partition Map Type: GPT (GUID Partition Table)

S.M.A.R.T. status: Verified


Crucial_CT240M500SSD1:


Capacity: 240,06 GB (240*057*409*536 bytes)

Model: Crucial_CT240M500SSD1

Revision: MU03

Serial Number: 1404096547D5

Native Command Queuing: Yes

Queue Depth: 32

Removable Media: No

Detachable Drive: No

BSD Name: disk1

Medium Type: Solid State

TRIM Support: Yes

Bay Name: SSD

Partition Map Type: GPT (GUID Partition Table)

S.M.A.R.T. status: Verified



So TRIM seems to be enabled.


But Blackmagic still shows something like 10-17 mbps for write


User uploaded file


Speedtest at terminal shows


write speed


1024+0 records in

1024+0 records out

1073741824 bytes transferred in 69.301462 secs (15493783 bytes/sec)



read speed


1024+0 records in

1024+0 records out

1073741824 bytes transferred in 0.132797 secs (8085587788 bytes/sec)

iMac, OS X Yosemite (10.10.2), iBooks Author 2.1.1

Posted on Mar 2, 2015 4:08 AM

Reply
12 replies

Mar 2, 2015 10:02 AM in response to Dmitry Ra

Your welcome. I think the issue is OS X is not designed for internal RAID solutions. I think if you had installed the SSD's into an external enclosure such as OWC's ThunderBay 4 mini RAID (http://eshop.macsales.com/shop/Thunderbolt/External-Drive/OWC/ThunderBay-4-mini- RAID5) that would work just fine. In the event you cannot find information regarding iMac's being able to handle internal RAID solutions then you may want to reach out to OWC and inquire.


I am by no means knowledgeable about RAID however I think that is where you may want to begin researching.


One sidebar...on my 2011 27" I installed a 240GB SSD and left the 1TB spinning HD in it. I was able to load OS X on the SSD and most of my files too. For my large libraries (photos, music, movies....) I keep these on external drives. In my case I kept my photo library on the internal HD because I wanted to keep the photos segregated from the other libraries. This seem to work fine and I have an external HD that use use to backup my internal HD so my photos have backup.


Glad your system is working as it should and good luck.

iMac 27 core i7 two ssd slow speed

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