Flash Drive Summary Table

Sequential read and write times generated by atto disk benchmark. for sequential access. The max numbers are typically for 4096k or 8192k file access. Random read and write times are generated by Crystal Disk Mark (4k access queue depth 32)

USB3 Flash DrivesSize Random
512k Write
Random
512k Read
Random
4k Write
Random
4k Read
Sequential
4k Write
Sequential
4k Read
Sequential
Max Write
Sequential
Max Read
Corsair Flash Voyager USB3 (plugged into USB2)16gb NA mb/secNA mb/sec NA mb/secNA mb/sec 4.0 mb/sec4.4 mb/sec 21 mb/sec28 mb/sec
Corsair Flash Voyager USB3 (plugged into USB3)16gb 1.644 mb/sec75.68 mb/sec 0.030 mb/sec10.57 mb/sec 10 mb/sec19 mb/sec 21 mb/sec74 mb/sec
Corsair Flash Voyager USB3 (plugged into USB2)32gb NA mb/secNA mb/sec NA mb/secNA mb/sec 4.5 mb/sec3.9 mb/sec 27 mb/sec23 mb/sec
Corsair Flash Voyager USB3 (plugged into USB3)32gb 1.529 mb/sec78.83 mb/sec 0.067 mb/sec7.667 mb/sec 16 mb/sec19 mb/sec 43 mb/sec80 mb/sec
Patriot Xpress (plugged into USB2)32gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.6 mb/sec5.3 mb/sec 19 mb/sec28 mb/sec
Patriot Xpress (plugged into USB3)32gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.7 mb/sec16 mb/sec 20 mb/sec32 mb/sec
Patriot Xpress (new) (plugged into USB3)32gb 1.304 mb/sec67.80 mb/sec 0.011 mb/sec9.334 mb/sec 2.3 mb/sec38 mb/sec 22 mb/sec80 mb/sec
PNY Turbo 2014128gb 10.69 mb/sec111.4 mb/sec 0.107 mb/sec4.151 mb/sec 13.8 mb/sec12.9 mb/sec 95.7 mb/sec137 mb/sec
PNY Turbo 2015128gb 10.71 mb/sec110.4 mb/sec 0.071 mb/sec4.611 mb/sec 15.1 mb/sec20.4 mb/sec 106.7 mb/sec138.4 mb/sec
PNY Turbo Nov 2015128gb 17.81 mb/sec84.74 mb/sec 1.11 mb/sec4.31 mb/sec 9.0 mb/sec19.4 mb/sec 90.3 mb/sec95.8 mb/sec
SanDisk Ultra USB 3.0 201664gb 0.505 mb/sec53.43 mb/sec 1.95 mb/sec4.11 mb/sec 2.3 mb/sec15.3 mb/sec 39 mb/sec101 mb/sec

USB Flash DrivesSize Random
512k Write
Random
512k Read
Random
4k Write
Random
4k Read
Sequential
4k Write
Sequential
4k Read
Sequential
Max Write
Sequential
Max Read
Corsair Flash Voyager8gb NA mb/secNA mb/sec NA mb/secNA mb/sec 2.5 mb/sec4.7 mb/sec 9 mb/sec22 mb/sec
Corsair Flash Voyager16gb NA mb/secNA mb/sec NA mb/secNA mb/sec 3.3 mb/sec5.3 mb/sec 18 mb/sec29 mb/sec
Corsair Flash Voyager (Nov 2008)32gb NA mb/secNA mb/sec NA mb/secNA mb/sec 0.6 mb/sec3.6 mb/sec 10 mb/sec19 mb/sec
Corsair Flash Voyager (Feb 2012)32gb NA mb/secNA mb/sec NA mb/secNA mb/sec 3.3 mb/sec5.2 mb/sec 18.6 mb/sec28.7 mb/sec
Emprex1gb NA mb/secNA mb/sec NA mb/secNA mb/sec 0.9 mb/sec4.4 mb/sec 3 mb/sec16 mb/sec
HP (PNY)8gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.2 mb/sec3.4 mb/sec 6 mb/sec18 mb/sec
Imation512mb NA mb/secNA mb/sec NA mb/secNA mb/sec 3.4 mb/sec3.2 mb/sec 5 mb/sec6 mb/sec
Micro Advantage64mb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.3 mb/sec3.8 mb/sec 1.4 mb/sec7 mb/sec
Patriot generic white flash512mb NA mb/secNA mb/sec NA mb/secNA mb/sec 0.59 mb/sec4.3 mb/sec 5 mb/sec12 mb/sec
Patriot generic white flash16gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.0 mb/sec4.5 mb/sec 15 mb/sec23 mb/sec
Patriot Dash32gb NA mb/secNA mb/sec NA mb/secNA mb/sec 0.8 mb/sec4.4 mb/sec 5 mb/sec16 mb/sec
PNY Attache16gb 0.670 mb/sec17.73 mb/sec 0.005 mb/sec2.611 mb/sec 1.4 mb/sec3.7 mb/sec 9.4 mb/sec18 mb/sec
Ridata128mb NA mb/secNA mb/sec NA mb/secNA mb/sec 0.9 mb/sec2.0mb/sec 2 mb/sec4 mb/sec
Sandisk Cruiser Titanium4gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.3 mb/sec2.6 mb/sec 8 mb/sec13 mb/sec
Sandisk Criuser2gb 2.589 mb/sec16.76 mb/sec 0.030 mb/sec3.020 mb/sec 1.8 mb/sec3.3 mb/sec 9 mb/sec17 mb/sec
Sandisk Criuser4gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.2 mb/sec3.3 mb/sec 8 mb/sec17 mb/sec
Sandisk Glide32gb 0.520 mb/sec20.28 mb/sec 1.654 mb/sec3.033 mb/sec 2.2 mb/sec4.4 mb/sec 6.8 mb/sec27 mb/sec
Sandisk Ultra Backup32gb 4.755 mb/sec24.89 mb/sec 0.005 mb/sec4.553 mb/sec 0.372 mb/sec5.285 mb/sec 18 mb/sec24 mb/sec
Simpletech2gb NA mb/secNA mb/sec NA mb/secNA mb/sec 0.1 mb/sec4.5 mb/sec 10.8 mb/sec25.8 mb/sec
TDK Go8gb 1.18 mb/sec17.0 mb/sec 0.011 mb/sec3.72 mb/sec 1.27 mb/sec4.5 mb/sec 12 mb/sec17 mb/sec
Ultra4gb 2.083 mb/sec19.46 mb/sec 0.020 mb/sec2.88 mb/sec 0.2 mb/sec3.5 mb/sec 6 mb/sec16 mb/sec
Generic 'key'8gb 0.653 mb/sec17.18 mb/sec 0.005 mb/sec4.082 mb/sec 1.9 mb/sec4.7 mb/sec 8.3 mb/sec17 mb/sec

CF and SD Flash DrivesSize Random
512k Write
Random
512k Read
Random
4k Write
Random
4k Read
Sequential
4k Write
Sequential
4k Read
Sequential
Max Write
Sequential
Max Read
Kingston SD1gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.13 mb/sec1.58 mb/sec 4 mb/sec8 mb/sec
Kingston micro SD1gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.13 mb/sec1.55 mb/sec 3.6 mb/sec8 mb/sec
Panasonic SD class 2512mb NA mb/secNA mb/sec NA mb/secNA mb/sec 0.996 mb/sec1.44 mb/sec 4 mb/sec8 mb/sec
Patriot micro SDHC class 1016gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.3 mb/sec2.9 mb/sec 16 mb/sec18 mb/sec
Patriot micro SDHC class 432gb 0.544 mb/sec14.31 mb/sec 0.875 mb/sec2.588 mb/sec 0.3 mb/sec3.9 mb/sec 5 mb/sec16 mb/sec
Patriot LX Series micro SDHC (USB3) class 1032gb 0.734 mb/sec45.83 mb/sec 1.483 mb/sec4.667 mb/sec 1.9 mb/sec6.7 mb/sec 13 mb/sec53 mb/sec
PNY SDXC (USB2) class 1064gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.22 mb/sec3.39 mb/sec 24 mb/sec30 mb/sec
PNY SDXC (USB3) class 1064gb 18.27 mb/sec67.78 mb/sec 0.731 mb/sec3.972 mb/sec 1.23 mb/sec4.88 mb/sec 59 mb/sec75 mb/sec
PQI Hi-Speed 80 SD (USB3)2gb 1.365 mb/sec11.10 mb/sec 0.028 mb/sec2.397 mb/sec 2.3926 mb/sec4.6 mb/sec 3.7 mb/sec11.4 mb/sec
Ridata SD128mb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.17 mb/sec1.46 mb/sec 4 mb/sec8 mb/sec
Samsung micro SDHC class 68gb 0.872 mb/sec22.64 mb/sec 0.046 mb/sec4.004 mb/sec 0.884 mb/sec4.2 mb/sec 12 mb/sec23 mb/sec
Samsung EVO plus micro SDXC class 10128gb 4.548 mb/sec67.53 mb/sec 0.886 mb/sec4.280 mb/sec 2.2 mb/sec5.9 mb/sec 25 mb/sec79 mb/sec
Samsung Pro plus micro SDHC class 10 U332gb 4.215 mb/sec67.74 mb/sec 2.489 mb/sec5.989 mb/sec 4.33 mb/sec9.10 mb/sec 74.5 mb/sec78.8 mb/sec
Sandisk Extreme III CF4gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.1 mb/sec1.8 mb/sec 7 mb/sec9 mb/sec
Sandisk Extreme III CF 30mb/s4gb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.2 mb/sec2 mb/sec 8 mb/sec9 mb/sec
Sandisk Extreme III SDHC (USB3) class 64gb 3.016 mb/sec22.87 mb/sec 0.026 mb/sec4.177 mb/sec 3.0 mb/sec5.2 mb/sec 20.9 mb/sec23.7 mb/sec
Sandisk Ultra micro SDHC (USB3) class 1032gb 0.802 mb/sec41.40 mb/sec 0.441 mb/sec4.425 mb/sec 2.7 mb/sec6.6 mb/sec 22 mb/sec45 mb/sec
Sandisk Ultra micro SDXC class 10128gb 0.704 mb/sec41.47 mb/sec 1.922 mb/sec4.127 mb/sec 1.9 mb/sec5.3 mb/sec 18 mb/sec45 mb/sec
Ultra SD512mb NA mb/secNA mb/sec NA mb/secNA mb/sec 1.11 mb/sec1.58 mb/sec 3 mb/sec8 mb/sec
Unirex SDHC class 10 (USB3)32gb 5.163 mb/sec66.94 mb/sec 1.636 mb/sec4.559 mb/sec 2.55 mb/sec6.83 mb/sec 20.9 mb/sec74 mb/sec

Corsair Flash Voyager 8gb

Purchased Oct-2011. The Flash Voyager is enclosed in a grippy rubber case. It is claimed to be waterproof and shock resistant. It can write at 9mb/sec and read at 22mb/sec. Not nearly as fast as the 16gb version of the Flash Voyager. Buy the bigger drive if you care about write speed.

Corsair Flash Voyager 16gb

Purchased Aug-2011. The Flash Voyager is enclosed in a grippy rubber case. It is claimed to be waterproof and shock resistant. It can write at 18mb/sec and read at 29mb/sec. My fastest USB flash drive! A bit bulky, but very fast and robust. Highly recommended.

Corsair Flash Voyager 32gb

Purchased Nov-2008. The Flash Voyager is enclosed in a grippy rubber case. It is claimed to be waterproof and shock resistant. It can write at 10mb/sec and read at 19mb/sec. A bit bulky, but fast and robust. Highly recommended.

Purchased Feb-2012. I decided to purchase a new Flash Voyager 32gb flash drive, due to the cheap price and 10 year warranty. The new drive looks just like the old drive, but as I suspected, it is much faster. The drive write speed is 18.6mb/sec and read is 28.7 mb/sec. Still no size written on the drive. Still highly recommended.

FAILED Emprex 1gb flash drive

I bought a 1gb flash disk from Emprex (because it was on sale). I copied some files to it. Some of the files got corrupted. I tried to reformat the drive. The reformat failed. I tried under linux as well. The reformat failed. I am unable to reformat it, and I am unable to copy files to it. I sent their tech support email. They said return it to the store I got it. I told them it was Fry's and they only accept returns for one month. I called their tech support department. They sent me a RMA form to fill out, and they asked for a copy of the sales receipt. I got a replacement drive, and it works normally.

HP flash drive (made by PNY) 8gb

Purchased Nov-2008. A normal flash drive. It can write at 6mb/sec and read at 18mb/sec.

Imation 512mb

An old flash drive. It can write at 5mb/sec and read at 6mb/sec.

Micro Advantage 64mb

A very old flash drive, my first in fact. Slowest flash drive I own. It can write at 1.4mb/sec and read at 7.7mb/sec.

Patriot 512mb

An old flash drive. It can write at 5mb/sec and read at 12mb/sec. Pretty fast for a flash drive.

Patriot 16gb

Purchased May-2011. It can write at 15mb/sec and read at 23mb/sec. Pretty fast for a flash drive.

Patriot Dash 32gb

Purchased Aug-2011. A flash drive with a sliding USB connector. It can write at 5mb/sec and read at 16mb/sec. Large capacity, and inexpensive, but a bit ugly and really slow writing speed. The generic patriot 16gb is 3 times faster at writing. Also someone forgot to include a LED on the drive, so you can't tell if there is any activity. Not recommended.

I thought the lack of a LED might indicate a defective drive. I contacted Patriot, who said there should be a LED. I sent mine back, and after a few weeks, I didn't get one back. I called them and asked what was happening. They said they got my drive, but didn't ship out a replacement. I asked when they might ship the drive, and they said they would ship it out as a priority. I got it today. No LED, and the same slow write speed. So in addition to making a really useless drive (no LED), their customer support is pretty poor. I won't be buying anything from Patriot.

The Patriot RMA department wants to send me another drive. I just got off the phone with their technical support department. They confirmed that the drive is designed to be inexpensive, and does not have a LED. It also has a very slow write speed. Too bad the RMA department doesn't seem to understand this. It would have saved me a hassle to send the drive back. The read speed is acceptable, but I cannot recommend this drive due to the glacial write speed and lack of a LED.

PNY Attache 16gb

Purchased May-2014. It can write at 9.4 mb/sec and read at 18 mb/sec. A basic, inexpensive, mainstream flash drive.

Ridata 128mb

An old flash drive. It can write at 2mb/sec and read at 4mb/sec.

FAILED Sandisk 2gb flash drive

I recently bought a Sandisk flash drive, because it was on sale, and they have a well known name. It came with U3 software which is supposed to allow data on the flash drive to be protected.

I tried copying 5 files that were approximately 350mbytes onto the drive. It was very slow. After a while, I got an error message about a failed write. I thought it might have something to do with the U3 software, so I tried to remove it. It cleverly reinstalled itself. I downloaded the Sandisk program to remove the U3 software. It told me that more than one drive was plugged into the USB on my computer. I unplugged everything, and got the same message. I tried the program on my notebook, and it worked. It turned out that I had an internal flash reader plugged into my USB on my main computer. It seems a stupid limitation that the program can't find or allow you to specify where the Sandisk flash drive is.

So, I tried copying the files again. It failed the same way. I called Sandisk tech support. They said all kinds of irrelevant things. They asked if I was copying it to the root directory, and said there might be a problem with that. They asked if I had any cdrom burning software and said there might a problem with that. They asked how big the files were and said there might be a problem with that. They had me reformat the flash drive. Finally, I said this was all bull, that FAT32 allows for pretty much any size file any where on the filesystem. I grabbed another 2gb flash drive which I happened to have lying around, and successfully copies the files on to that. Finally they admitted that it might be possible that their brand new flash drive might be defective. They said I could RMA it, but it would be faster to return it to where I bought it. I agreed. I know that inexpensive hardware can fail, but having it not work from the start, where a simple test would reveal the problem is inexcusable. I am very disappointed with the quality control of SanDisk. I am also very disappointed with the quality of their tech support. The only thing they didn't claim could cause a problem was the direction I was pointing the flash drive. They should not mention bogus things. It can easily confuse the less technically adept.

Sandisk Cruiser Titanium 4gb

Purchased Jun-2007. A flash drive with a sliding USB connector. It isn't made out of titanium but out of 'liquid metal', which is roughly 10% titanium. It is robustly constructed, and all metal so you won't wear through it if you have it on your keyring. It can write at 8mb/sec and read at 14mb/sec. Recommended for a reasonably capacity, reasonably price, reasonably compact, reasonably robust drive. It is my every day carry.

Sandisk Cruiser 4gb

A flash drive with a sliding USB connector. A few years old. It can write at 8mb/sec and read at 17mb/sec. You will never lose the cap.

Sandisk Glide 32gb

Purchased Nov 2012. A flash drive with a sliding USB connector. I just bought three of these, as there was a black friday sale. This drive did not work in the front connector on my computer. I called up Sandisk technical support and they told me to try a USB connector on the back of my PC. I was quite dubious of this, but it worked. It turns out that this drive needs quite a bit of power, and for some reason, the front panel connector of my computer isn't supplying enough power. It has a hole in the plastic body for attaching to a keychain or the like. Not as robust as a metal hole. Write speed is 6.8mb/sec at 16kbyte writes, but goes down to 2.6 mb/sec for larger writes, which I have never seen before. Read speed is 27 mb/sec which is very good for a USB2 drive. All three of these failed within a week, but Sandisk replaced them with the Ultra Backup reviewed below.

Sandisk Ultra Backup 32gb

Acquired Jan 2013. A flash drive with a sliding USB connector. It is pretty bulky for a flash drive. There is no drive access light, which seems like a bad idea to me. It 'features' U3 backup software, which is not something I want. Fortunately, it is simple to download the 'launchpadremoval' program. It requires windows to work, but it does remove the U3 software. I don't like how bulky the drive is. I don't like how to attach a cord to the drive either. It is all plastic. I think the basic cruiser design is far more elegant, and takes up about half of the volume of the ultra backup drive. 4kb writes are almost 6 times slower than the Glide, which isn't a fast drive. My Corsair Voyager USB2 is about 10 times faster at 4k writes. Random 4kb writes are 330 times slower than the glide (which is faster than most flash drives). The Ultra Backup is twice as slow as any drive I have measured for random 4kb writes. Not recommended.

TDK Go 8gb

Purchased Dec-2012. It has no access light. It can write at 12mb/sec and read at 17mb/sec. Random 4k writes are very slow. Not recommended.

Ultra 4gb

Purchased Jan-2007. It can write at 6mb/sec and read at 16mb/sec. Slow, but not nearly as slow as the patriot dash, which is 4 years newer. Reasonable value in its day.

Generic 8gb 'key'b

Free from trade show, 2015. This is a flat aluminum flash drive that looks like the outline of a key. I cut it down to be smaller because I keep it on my keychain. Reasonably fast for a USB2 drive.

Corsair Flash Voyager 16gb USB3

Purchased Aug-05-2012. The Flash Voyager is enclosed in a grippy rubber case. It is claimed to be waterproof and shock resistant. It is a USB3 drive. According to the manufacturer, it has a write speed of 18mb/sec and a read speed of 75mb/sec. The Patriot Xpress claimed very high read and write speeds and failed to deliver, so I was curious how the Corsair USB3 drive would perform. Using a USB2 port, it can write at 21mb/sec and read at 28mb/sec, Using a USB3 port, it can write at 21mb/sec and read at 74mb/sec. So the Corsair drive proves that my USB3 port is working just fine, and that the Flash Voyager USB3 specs are correct. It is much slower than the Corsair Flash Voyager 32gb USB3 drive, but meets its published specs. The fastest read speed I measured was 74.773 mb/sec which is close enough to 75mb/sec. If you really want speed, but the 32gb version of this drive. Looking at the 4k write speed, it does 4mb/sec with USB2 and 10 mb/sec with USB3. This is significantly faster than any other drive except my 32gb corsair flash voyager 32gb drive. A bit bulky, but fast and robust. Highly recommended.

Corsair Flash Voyager 32gb USB3

Purchased Mar-2012. The Flash Voyager is enclosed in a grippy rubber case. It is claimed to be waterproof and shock resistant. It is a USB3 drive. According to the manufacturer, it has a write speed of 40mb/sec and a read speed of 80mb/sec. The Patriot Xpress claimed very high read and write speeds and failed to deliver, so I was curious how the Corsair USB3 drive would perform. Using a USB2 port, it can write at 27mb/sec and read at 23mb/sec, Using a USB3 port, it can write at 43mb/sec and read at 80mb/sec. So the Corsair drive proves that my USB3 port is working just fine, and that the Flash Voyager USB3 specs are correct. It also shows that the Patriot Xpress drive's specs are a factor of 2 higher than reality. My fastest USB flash drive! Looking at the 4k write speed, it does 4.5mb/sec with USB2 and 16 mb/sec with USB3. This is significantly faster than any other drive. A bit bulky, but very fast and robust. Highly recommended.

Patriot Supersonic Xpress 32gb

Purchased Nov-2011. It is my first USB-3 drive. It is advertised to write at 25mb/sec and read at 60mb/sec. Using the ATTO Disk Benchmark (which I use for all my drive speed tests), it did 19mb/sec write and 28mb/sec read with my USB-2 controller. Using my USB-3 pci-e adapter it did 20mb/sec write and 32mb/sec read. It even has a blue LED. Perhaps my USB-3 controller isn't as fast as some, but the results are just barely faster than my corsair 16gb flash drive. The slot for a keychain or whatever is quite thin and others have reported it breaks in a month of use.

Well, I ended up buying a Corsair Flash Voyager 32gb USB3 drive. It worked at better than the advertised speed, which was 40mb/sec write and 80mb/sec read. I sent the flash drive back to Patriot, as it did not meet their specs. The new drive did 18mb/sec write and 28mb/sec read with my USB-2 controller. Using my USB-3 controller is did 22.7mb/sec write and 80mb/sec read, which is a bit slower than advertised for write and faster for read. It is substantially faster than the first one I bought.

PNY Turbo 128gb

Purchased Jan-2014, $40 after 2 rebates. In reviews, it is claimed the write speed is up to 130 mb/sec and read speed is 190mb/sec. I was able to measure 95.7 mb/sec writes and 137 mb/sec reads, which isn't nearly as fast. It doesn't work in many computers using a USB2 port. I have a dell i7 notebook which predates USB3, and it doesn't get recognized in any port. I also have a Asus motherboard which predates USB3 and the drive is not recognized. The drive itself is quite compact. There is a sliding cover for the USB3 connector. It locks in place when covering the connector, but slides around when not covering the USB connector. I have not seen such a poorly designed sliding USB flash drive. I cannot recommend it for general use due to the poor sliding cover design. I have several other USB3 thumb drives and they all work in USB2 ports. This is a fatally flawed design. Also I have called PNY several times, and they never answer their phone. Not recommended except if all of your USB ports are USB3.

I am a bit slow, but I bought some other USB3 flash drives and realized that this one was defective because it was not recognized un USB2 port. I called PNY and I was told since it was over a year old, it was out of warranty. However, when I purchased it from Tiger Direct, the Tiger Direct web site said it had a 'lifetime warranty'. I kept a copy of the Tiger Direct description. I called PNY back and said I thought it had a lifetime warranty. Since it was only about 14.5 months since I bought it, they gave me a RMA number for it.

The replaced drive works in all the USB2 ports I have tried it in, which is a big improvement. It is a tiny bit faster, though the write speed is a bit odd. For sequential writes, 32k is 91mb/sec, but 64k is only 48mb/sec. 128k is 88mb/sec, but 256k is 45mb/sec. The pattern repeats being fast for 32k, 128k, 512k, 2048k, and being slow for 64k, 256k, 1024k, 4896k and 8120k. Still, not near the advertised speed of 130mb/sec write and 190mb/sec read. Perhaps PNY has a magic setup. Other flash drives I have bought have met or exceeded the published specs. Draw your own conclusions.

I bought 2 more of these drives, because they were $20 each. Something has changed with respect to the performance. The good news is that random writes are faster. The bad news is that everything else is slower. PNY does not advertise a specific speed for these drives, and they are reasonably fast. Just not as fast as they used to be.

SanDisk Ultra USB 3.0 64gb

Purchased May-2016 for a screaming deal of $1. Comes with a 5 year warranty, which is quite reasonable for a flash drive. A whole lot better than PNY's one year warranty. This is a nice compact flash drive with a retractable tip. It also has a decent hole for a lanyard or keyring. There is a LED, which is blue and quite dim. I would prefer a really bright LED, to make it obvious when the drive is being accessed. The write speed is pretty slow, with a best case of 39 mbytes/sec and a typical large block write speed of 21 mbytes/sec. Read speed is quite good at 101 mbytes/sec (which meets the advertised speed of up to 100 mbytes/sec). Certainly not a high end USB 3 flash drive, but fine as a general purpose flash drive. Random 512k writes are the slowest I have measured for a USB 3 drive by over a factor of 2. Random 4k writes are surprisingly good.

Patriot micro SDHC LX 16gb

Purchased Dec-2011. This is a micro SDHC card, rated as 'class 10'. This means it is supposed to sustain a write speed of 10mbytes/second. I measured a write speed of 16 mbytes/second and a read speed of 18 mbytes/second. This is well above spec, and pretty fast for any flash drive.

Patriot micro SDHC LX 32gb class 4

Purchased May-2011. This is a micro SDHC card, rated as 'class 4'. This means it is supposed to sustain a write speed of 4mbytes/second. I measured a write speed of 5 mbytes/second and a read speed of 16 mbytes/second. This is above spec, and was a good value at $12 after rebate.

Patriot micro SDHC LX 32gb class 10

Purchased Nov 2013 for $10 after rebate (black friday)This is a micro SDHC card, rated as 'class 10'. This means it is supposed to sustain a write speed of 10mbytes/second, however, I think the 'class' numbers only go up to 10. I measured a write speed of 13 mbytes/second and a read speed of 53 mbytes/second (using a USB3 card adapter). It is much faster than the Sandisk Ultra 32gb micro SDHC card at 4k random reads and writes. This is well above spec, and was a great value at $10 after rebate.

PNY Elite Performance SDXC 64gb

Purchased Nov-2013, $20 after rebate. This is my first SDXC drive. It turns out that SDXC slots will only recognize 32gb of SDXC flash drives. They also do 1 bit transfers, not 4 bit transfers. They also run at a higher voltage than the SDXC protocol. Also they don't know seem to know about the ex-fat file system, that it the SDXC default. The PNY drive is a 'class 10' drive, but the claimed write speed is 50 mbytes/second and read speed is 90 mbytes/second. Using the atto disk benchmark and a USB3 adapter I was able to measure write speeds around 50 mbytes/second on transfers 128 kbytes or larger. The best write speed I measured was 59 mbytes/second on a 128 kbyte transfer. At larger transfers, the write speed dropped to 45-47 mbytes/second. So the claimed 50 mbytes/second write speed is justified. As for read speeds, the highest I measured was 75.559 mbytes/second on a 64 kbyte read. Bigger transfers dropped down to 72 mbytes/second. So I was unable to replicate the claimed 90 mbytes/second read speed. Perhaps my USB3 card reader is too slow, or perhaps PNY's claim is higher than reality. As this is my only SDXC card, it is unclear what is limiting the speed.

I contacted PNY in Nov 2013, but I have not heard back from them. I also called them, and got an answering machine from tech support.

SanDisk micro SDXC 32gb

Purchased Jun-2015, $13. This is a high performance micro SDHC card which I intend to use for my new raspberry pi II B. The first thing I noticed was the adapter has several cuts on the contacts. It may have been from the way I removed it from the packaging, but if so, I think it a fault of the packaging. I called Sandisk, and they said that was normal, even thought I though it looked quite odd. I tried it in my computer and it didn't work. I tried a different adapter which did work, so the adapter is defective. No problem, the card has a 10 year warranty. I called Sandisk back up, and they said too bad, only the card has a 10 year warranty, the 'accessories' have no warranty. I was a bit upset but they cleverly hung up on me. I called Amazon where I purchased it, and they said no problem, I can return it or exchange it for 30 days. They arranged an exchange. Get a clue Sandisk.

Next, I measured its performance. Right on the package it says speed up to 48 mbytes/second. I measured it with atto disk benchmark and I was able to get just under 45mbytes/second read speed. I measured it with crystal disk mark and was able to get just under 44 mbytes/second. Perhaps Sandisk has some magic benchmarking utility that reports numbers roughly 10% faster than the most common benchmarking tools, but I doubt it. Random 4k writes (which is important for running an OS s 441kbytes/sec which is pretty crappy. The Patriot SDHC class 4 micro SDHC is twice as fast, and it isn't a very fast part. Next time, I will go with Samsung.

Samsung EVO plus micro SDXC 128gb

Purchased Sep-2015, $50AR. This is the highest capacity micro SDXC card that can be purchased to date. On the package is says 80mb/sec writes and 20mb/sec reads. Using atto, I was able to measure 79mb/sec reads, which is a bit slower than advertised. I was also able to measure 25mb/sec writes which is faster than advertised. I got similar numbers with CrystalDiskMark. It is not nearly as fast as the PNY Elite SDXC card. On the other hand, it is a micro SDXC card. These are typically used in cell phones, not in middle to high end digital cameras. It is amazing that anyone can cram 128gb in such a small form factor. It comes with a 10 year warranty. Samsung is a very reputable company. Last year I bought a Dandisk 128gb micro SDXC. A year later, the price has gone down by 50%.

Samsung Pro plus micro SDXC 32gb

Purchased Apr-2016, $10 (a screaming deal). This is probably the fastest micro sdhc card to date. Samsung claims a max write speed of 90 mbytes/sec and a max read speed of 96 mbytes/sec. I was unable to get numbers as high, but I did measure write speeds over 73 mbytes/sec starting with 64 kbyte transfers and read speeds over 77 mbytes/sec starting with 64 kbyte transfers. The 4k random write speed is 4.33 mbytes/sec which is the highest I have measured in a sd card the 4k random read speed is 6 mbytes/sec which is also the fastest I have measured in a sd card. It is slower than a decent SSD, but faster than any card. I will be using it as the main drive in my new raspberry pi 3. It comes with a 10 year warranty. Samsung is a very reputable company and they make the fastest flash memory and SSDs.

SanDisk Ultra micro SDXC 128gb

Purchased May-2014, $120. This is the highest capacity micro SDXC card that can be purchased to date. It is not nearly as fast as the PNY Elite SDXC card. On the other hand, it is a micro SDXC card. These are typically used in cell phones, not in middle to high end digital cameras. It is amazing that anyone can cram 128gb in such a small form factor. It comes with a 10 year warranty. SanDisk is a very reputable company that actually has phone tech support with real people, unlike PNY who I have never been able to contact tech support by phone. Based on my experience, SanDisk is the most reputable flash card vendor.

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