SanDisk Extreme 64GB 3.0 - R: 200MB/s, W: 8MB/s

I’ve had this drive for 7 months and I feel like it used to be faster. I think I reformatted it to exFAT when I had issues with it storing large files since I was intalling games on it.

I noticed today that while it still reads at 200MB/s, it only writes at 8MB/s. And duplicating a file (even a single, large file) only manages 3MB/s.

Any idea why this is happening/how to fix it?

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in that case you can try to format the drive with the computer and then try again to copy some files to see if the speed again is so slow. if that also is very slow you can test the speed with the crystal disk mark and send the speds to sandisk to see if they are indeed very slow. 

you can download the software from this link

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Any idea why this is happening

File fragmentation would be my primary guess but dead blocks can’t be completely ruled out. Nor can electrical contact oxidation.

Try running a defrag app on it.  See what it shows and if it helps.

Try running CHKDSK on it.  With no flags and if errors are reported with the /F flag.

Try cleaning the USB contacts, on the drive and on the port, with emory paper.  Just lightly. 

And you can try backing up your files, reformating it, exFAT, as deponia suggested, then restoring your files.

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How could this be possibly related to file fragmentation? It’s a flash memory for crying out loud. You’d have to have a ton of super-small files to choke it like that. I have exactly the same problem with that pendrive. Reads are awesome, writes are a total failure. (190/8)

I’m trying to move a ~50 GiB file from my laptop to my desktop. Getting 8MBps is something I can get from a 64GB 8€ stick, not something I bought for ~80€. I get higher speeds sending those files thru SMB over the 802.11N for God’s sake! It’s easier to remove the drive from notebook, plug it into the desktop and copy the files that way. Ridiculous to the point it’s not even funny.

I’ve checked if the offset is okay. It is. I’ve reformatted drive to 8K, 32K & 64K sectors. The difference is negligible. I’ve even zeroed the drive from first to last byte. No use.

Here’s the output from CDM:

and second one, with bigger sample:

Here’s what I found in one of the reviews: (source: )

I don’t scream for that additional 60 Megs on read and 40 Megs on write. Right now I’d be happy getting 40 MBps of writes - less than quarter of what’s guaranteed, still 5 times more than I have now. It’s devastating that my older 32 gig drive on usb 2.0 (other manufacturer) is actually faster than this one. I really want to know why it’s happening, because - as you can see - I’m not the only one with that problem.

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This is related to FAT corruption, quoting from Sandisk tech help. Their official solution: DO NOT FORMAT.

Any format you perform will bring the writing speed down. I went from having 200 MB/s to 10 after two full formats.

A solution I found: ATA secure erase deep format using Parted Magic tool or similar. This will restore the original speed levels. Not a basic user friendly process, though…

Sorry but this is bull***t. It’s like trying to explain to somebody that rearranging car’s driver seat by a level that’s been designed to do that, will make it go 10km/h instead of 200km/h. I don’t buy it. Moreover, I have RMA’d my stick and after few e-mails that I’ve exchanged with the support (disabling the write cache in the meantime, to show that the sequential top write speed is about 60 Megs per second in a synthetic test and about 5,5MBps in a long run (copying a file that had over 10 Gigs) they’ve said that they acknowledge that the stick isn’t offering what it should and they’ve replaced it. The old stick was recognized as fixed drive (and, as far as I know, they’ve stopped selling those long time ago because I don’t know why), the new one is recognized as a removable, though both have same model/part number.

I’ve backed up first 50k sectors of the drive, in case I needed to revert to the stock. Then I’ve done the tests in the CDM and a real-life performance. 150-170 Megs on write was a value that was easily achievable. Then I’ve formatted the drive with the factory alignment (16K free space on the beginning of the drive). NTFS caused reads to go down a bit, but at the same time, there was an improvement in write speeds, especially looking at the random writes. Then I’ve completely erased the drive structure and formatted the stick. The start sector was 0, so there was no free space at the beginning whatsoever. No difference (or rather a difference that one could account for a statistical error). The stick just flies when it comes to the write speed. And now copying back and forth files that have even dozen Gigs in size is a pleasure. Not a horror, when write speed is dropping over the time to a single digit value that’s not even close to 9…

I wanted to say Thank You to SanDisk that the “lifetime warranty” is not only an empty slogan, but something that when you put a load of money on the table in the shop for their product, you can really be sure that they won’t leave you alone in unpleasant situations like the one mentioned here. Many offer that, but not everybody goes by the rules when things go wrong. A big thumbs up for that.

No need to throw the b***s**t tag on my comment, thank you very much. Just posting my experience here with this flash drive. Looks like you also have decent speeds. In my case, since I am using it as a windows to go usb, I noticed a severe slowdown after preparing the drive for a secokd time.

Maybe I used the wrong system file or a bad sector size on the flash drive. I used the aforementioned method to fix it and I am sharing it here, that’s all.

You said “quoting from Sandisk tech help”, therefore it’s not your opinion but their statement which you just mentioned. And my comment was about their statement. Apart from that one thing, which, as I want to emphasize, is SanDisk thesis, there’s nothing in your comment that can be thrown upon, especially a poo. :wink: As you can see, I’m a tech savvy, so I wouldn’t call bulls**t on anything that could be true, even partially.

Just to clarify - what you essentially did was a data-destructive way of performing “TRIM” command on the stick. Since those memories are practically an SSD with an USB port, they need to flag sectors that are ready-to-erase so a garbage collector will perform its work and prepare them for next write cycle. For some reason (firmware bug perhaps?) the controller didn’t do its work properly (or rather “at all”) and after you’ve written a dozen Gigs to the stick and deleted them now & then, all of the (free at the time) drive space was marked as ready-to-erase. Crippled garbage collector didn’t do anything about it, therefore every write that drive wanted to perform had to be preceded by an erase cycle, which changes the “write” operation to “read-erase-change-write”, where the deletion takes a ton of time, resulting in write speeds that are so poor that you’d consider dismantling one computer and plugging your drive to the other because moving data that way would still be faster than copying it through the stick that’s slower on writes than 10 Megs a second.

And since the safe erase did bring back the performance of your hardware, you can be more than sure that after some time you’ll be back in square one, because if the garbage collection doesn’t work, when you start to run out of free pages (and you eventually will), the write speed of stick will drastically decrease to a level of single-digit Megs per second.

Filesystem doesn’t have anything to do with it. Moreover - if somebody says that it’s due to the “FAT corruption”, then I’d like to ask one thing - what if one does have an NTFS file system? It doesn’t have a File Allocation Table. What if somebody did format the drive to, let’s say, EXT4? Or HFS+?

Same thing for sector sizes. It doesn’t really matter how big sector you decide to use. 512B? 4K? 16K? Or maybe 64K? It doesn’t matter, as long as the beginning of the drive starts at sector that’s a non-zero power of 2 OR exacly 0 to avoid misalignment between physical and logical structure of the drive.

Bearing that in mind, after you’ve done the secure erase, you’ve completely destroyed any structures that the manufacturer could have created (data offset would be one and only thing that could matter here, but since you didn’t format the drive later under SSD-unaware XP or W98, it’s not an issue), still you got your speed back, so it only confirms that the stick is faulty.

Replace it as soon as possible, because you’ll hit the wall sooner or later and since you’re running an OS on that, it’ll be a real pain to use a drive that’s as slow on the writes as an HDD that’s on PIO mode 1. :slight_smile:

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