Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I just replaced my Samsung 830 256gb SSD with a 1TB 850 Evo SSD (I am running OSX in Thunderbolt external) and my R/W speeds are significantly slower. I ran a speed test with drive in OWC USB 3 enclosure and I am getting the same speeds as when I am using the drive in Thunderbolt enclosure. The drive is supposed to get up to 540MB/s and I am getting between 350-390. I have enabled trim (El Capitan) and this makes no difference. Is there something wrong? Shouldn't I be getting better speeds with Thunderbolt?

1cBfh+
 
I have Samsung 850 Pro's in RAID 0 on two different Mac's. A MacMini internally using OSX RAID 0 and in a Akitio Thunder2 Mini (Hardware RAID 0). Both Suck! I've seen both degrade from 700 MB/s write speeds down to 200-250 MB/s Writes.

I didn't see an obvious resolution/conclusion to this thread.... Has anyone cracked this yet? Or are people returning them to Samsung?
 
I'm gonna hijack this thread as well. A year ago I successfully set up my MBP 15" with two Samsung 850 Pro 512GB SSDs in RAID 0. Those were my read/write speeds:
RAID0.jpg

Now, a year later, I get these write speeds:
Screen Shot 2017-11-01 at 23.00.26.png

I haven't found a solution yet. If anyone knows what to do, please share your insights. Help is much appreciated. Thank you.
 
I actually fixed my problem on both of my Macs by 1st Un-RAID'ing the two Samsung 850 drives, then re-formatting by writing zero's to the entire drive. This restored the original read write speeds I got when I bought the drives. I reformatted with zero's using a program called SoftRAID.

The cool thing about softRAID is it is free if you only want to do RAID 0 (and not RAID 5 etc). This gives you the utility function to write all zeros do you drive. I actually switched from hardware raid to software raid with almost no loss in performance

The other problem you have is it with normal hardware raid you cannot utilize Trim Enabler. However, with softRAID you can. I am hoping with soft raid and a trim enabler, I can avoid this problem in the future. Time will tell.



I'm gonna hijack this thread as well. A year ago I successfully set up my MBP 15" with two Samsung 850 Pro 512GB SSDs in RAID 0. Those were my read/write speeds:
View attachment 730243

Now, a year later, I get these write speeds:
View attachment 730245

I haven't found a solution yet. If anyone knows what to do, please share your insights. Help is much appreciated. Thank you.
 
I would fault the testing software, personally, and would check with different software. The read speed looks about right mind you.
 
back up and running fine:
Screen Shot 2017-11-13 at 14.02.34.png

things I did differently this time:

1. Backup with CCC to an external and bootable drive
2. Bootup while holding down CMD + R
3. Open up Terminal and destroy RAID settup (diskutil appleRAID delete diskidentifier)
4. Go to Disk Utility and reformat one of the drives as Master Boot Record – the other as Apple Partition MapScreen Shot 2017-11-13 at 14.09.29.png
5. Create RAID in terminal
6. Reboot while holding down option
7. Boot from your bootable backup drive
8. Open up DiskSpeed Test to determine whether your speeds look a-ok.
9. Copy files from backup to your main drive. Done.
 
SATA 3 SSDs do not work reliably at full speed in the optical bay of 2011 Macbook Pros.

I have a MBP late 2011 17" and have a 1TB Samsung Evo SSD working like a clock in my optical bay as my "everything drive". I know they say it can't be done, but a metal optical drive caddy seems to work a lot better than OWC's data doubler. Also, the later the build in 2011 apparently the more likely it is to work. I'm getting SATA III speeds - 450 MB/s write and 500 MB/s read in the optical bay. Optical caddy bought on Amazon from Highfine ($8.99).
 
IIRC...

SATA-connection of the HD-Bay of MBP 2011 and later are SATA III, but SATA connection of their optical bay is just SATA II - so even the fastest SSD in position of the optical bay will NEVER be faster than about 250 MB/s.
Which is nothing but logical since the CD/DVD Drive never will be even nearly as fast...you can proof this by exchanging the two SSDs in HD-Bay <---> optical Bay
 
back up and running fine:
View attachment 735195

things I did differently this time:

1. Backup with CCC to an external and bootable drive
2. Bootup while holding down CMD + R
3. Open up Terminal and destroy RAID settup (diskutil appleRAID delete diskidentifier)
4. Go to Disk Utility and reformat one of the drives as Master Boot Record – the other as Apple Partition MapView attachment 735196
5. Create RAID in terminal
6. Reboot while holding down option
7. Boot from your bootable backup drive
8. Open up DiskSpeed Test to determine whether your speeds look a-ok.
9. Copy files from backup to your main drive. Done.



Hello , is this a stable solution?
 
back up and running fine:
View attachment 735195

things I did differently this time:

1. Backup with CCC to an external and bootable drive
2. Bootup while holding down CMD + R
3. Open up Terminal and destroy RAID settup (diskutil appleRAID delete diskidentifier)
4. Go to Disk Utility and reformat one of the drives as Master Boot Record – the other as Apple Partition MapView attachment 735196
5. Create RAID in terminal
6. Reboot while holding down option
7. Boot from your bootable backup drive
8. Open up DiskSpeed Test to determine whether your speeds look a-ok.
9. Copy files from backup to your main drive. Done.
[doublepost=1521899589][/doublepost]YEP, that's essentially what I did. Works!:cool:
[doublepost=1521899664][/doublepost]
Hello , is this a stable solution?

Yep, that's essentially what I did. See above. Works
[doublepost=1521900496][/doublepost]
Hello , is this a stable solution?

Yep, that's essentially what I did. See above. Works
 
Great, i am about to create a Raid0 in MacPro1.1 with 2 SSD 512 Evo 850 and would not like to incur in similar problems like dropdown of performance after some use. I don't know if the same would apply to my case as i would create software Raid0 on 2 SataIII SSD mounted in two SataII Drive Bays of MacPro.

Would you please share how to create the Raid0 in terminal? Thanks!
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.