Samsung 840 Pro on Mac - Huge Slowdowns

[Noorae]

Important Specs up front:

• Late-2011 27" iMac
• SSD connected to internal SATA-3 connector (SATA-3 confirmed in system profiler)
• 256GB Samsung Pro installed (Was previously using 120GB OWC 6-gigabit Pro SSD)
• TRIM - disabled
• Currently more than 50% of capacity is available
• AHCI 1.30 Mode
• DXM03B0Q Firmware

Detail of issues:

I installed this larger drive on my iMac for space. Previous drive tested in the 250MB/sec range for write and a little faster for read even though was SATA-3. I suspect this had a lot to do with the drive being nearly full. Using Blackmagic and Nova to verify speeds.

I installed the new drive and did not clone, choosing a fresh install on 10.8. (Before install of OS, I did a "seasoning" writing zeros to the drive with the Disc Utility.) After fresh installed, I verified 450MB+/sec on read and writes on both test programs. I then installed applications (nothing odd - mostly PS CS6, Office, and a few support programs) and copied over documents. Was at about 42% of the drive full. No preferences or caches were copied, choosing instead to regenerate those and re-do preferences. Some of the caches grew very large (10+ GBs) overnight, but the settings were changed, caches cleaned up, and the drive currently sits at about 48% filled.

And now the drive is terribly slow. It feels sluggish, and writes are in the 40-70MB/s range with read about 2-3 times as fast.

What happened, and can it be fixed? What other information would be helpful?

Thanks!

 

[philipma1957]

Important Specs up front:

• Late-2011 27" iMac
• SSD connected to internal SATA-3 connector (SATA-3 confirmed in system profiler)
• 256GB Samsung Pro installed (Was previously using 120GB OWC 6-gigabit Pro SSD)
• TRIM - disabled
• Currently more than 50% of capacity is available
• AHCI 1.30 Mode
• DXM03B0Q Firmware

Detail of issues:

I installed this larger drive on my iMac for space. Previous drive tested in the 250MB/sec range for write and a little faster for read even though was SATA-3. I suspect this had a lot to do with the drive being nearly full. Using Blackmagic and Nova to verify speeds.

I installed the new drive and did not clone, choosing a fresh install on 10.8. (Before install of OS, I did a "seasoning" writing zeros to the drive with the Disc Utility.) After fresh installed, I verified 450MB+/sec on read and writes on both test programs. I then installed applications (nothing odd - mostly PS CS6, Office, and a few support programs) and copied over documents. Was at about 42% of the drive full. No preferences or caches were copied, choosing instead to regenerate those and re-do preferences. Some of the caches grew very large (10+ GBs) overnight, but the settings were changed, caches cleaned up, and the drive currently sits at about 48% filled.

And now the drive is terribly slow. It feels sluggish, and writes are in the 40-70MB/s range with read about 2-3 times as fast.

What happened, and can it be fixed? What other information would be helpful?

Thanks!

so you wrote over the entire drive withs zeros? 1x 2x or 7x. This was a new drive before the 0 overwriting . I do not think writing a new drives with 0's is a good idea.

 

[VirtualLarry]

so you wrote over the entire drive withs zeros? 1x 2x or 7x. This was a new drive before the 0 overwriting . I do not think writing a new drives with 0's is a good idea.

For magnetic HDDs, doing a surface scan followed by a write zeros pass followed by a surface scan can be a good idea to test the drive.

But for an SSD? No way. What you need to do, to restore the drive performance, is to TRIM the entire user LBA space, and then let it sit there for a few hours to internally garbage-collect, and THEN re-install your OS, WITHOUT writing to the entire drive.

Remember, when you write to the entire user LBA space, even if writing zeros, those sectors are considered "in-use" and written to, even if the OS doesn't use them. So when you then write to the drive, it has to do a read-copy-write pass, instead of just a write pass. It slows it way down.

 

[Elixer]

Yeah, big mistake to write all 0's to the SSD, and also not to have TRIM enabled.
These drives really need TRIM enabled to behave optimally.

 

[Hellhammer]

Enable TRIM and let the SSD idle for some time, that should do the trick.

 

[Brahmzy]

lol, I'd secure erase that drive stat.

 

[Noorae]

so you wrote over the entire drive withs zeros? 1x 2x or 7x. This was a new drive before the 0 overwriting . I do not think writing a new drives with 0's is a good idea.

So I'm really surprised to hear this from everyone. I used Disc Utility's secure erase function in one pass, with the idea of testing all the NAND on the drive. I know we did this for HDD to make sure all blocks were good before using the drive. Doesn't a fresh drive get shipping with all bits set to 0 anyway? From a technical standpoint, what is the error?

I've always used Sandforce drives on my macs, so TRIM as I understood wasn't necessary. Is that different with samsung drives? Is there a prefered TRIM-enabling solution for macs?

Thanks!

 

[Jocelyn84]

I've always used Sandforce drives on my macs, so TRIM as I understood wasn't necessary. Is that different with samsung drives? Is there a prefered TRIM-enabling solution for macs?

Thanks!

http://www.groths.org/?page_id=322

 

[Noorae]

For magnetic HDDs, doing a surface scan followed by a write zeros pass followed by a surface scan can be a good idea to test the drive.

But for an SSD? No way. What you need to do, to restore the drive performance, is to TRIM the entire user LBA space, and then let it sit there for a few hours to internally garbage-collect, and THEN re-install your OS, WITHOUT writing to the entire drive.

Remember, when you write to the entire user LBA space, even if writing zeros, those sectors are considered "in-use" and written to, even if the OS doesn't use them. So when you then write to the drive, it has to do a read-copy-write pass, instead of just a write pass. It slows it way down.

Thank you VirtualLarry, you answered my first question. I was really surprised to hear that even writing 0's the drive considers the sectors in use. Is this garbage collection process of TRIM basically returning it to an original, usable state?

Do I need to TRIM my Sandforce (SATA3) drives?

 

[Emulex]

you can 1. use trim enabler for mountain lion
or 2. OP the drives about 25%

or both

 

[Noorae]

Just reporting back. After turning on TRIM and letting it idle, the speeds did return to nearly out-of-the-box performance. I'll be avoiding the secure erase pre-install in the future!

 

[dave_the_nerd]

http://www.groths.org/?page_id=322

I read the OP and was basically just skimming the thread to see if anybody mentioned this one. It's awesome.

 

[tweakboy]

Since its a MAC it controls you and gives you no controls like Windows.

sorry nothing you can do about it,, RMA get a new one... end of story. gl