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?
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*TERRIBLE* "Write" speeds w/2x Samsung 850 Pro Internal SSD (RAID-0).. HELP! (+pics)
- Thread starter lip5016
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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 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:
Now, a year later, I get these write speeds:
I haven't found a solution yet. If anyone knows what to do, please share your insights. Help is much appreciated. Thank you.
Now, a year later, I get these write speeds:
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.
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 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:
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 Map
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.
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 Map
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.
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
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
[doublepost=1521899589][/doublepost]YEP, that's essentially what I did. Works!
[doublepost=1521899664][/doublepost]
Yep, that's essentially what I did. See above. Works
[doublepost=1521900496][/doublepost]
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!
Would you please share how to create the Raid0 in terminal? Thanks!