Solid State 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)

Solid State 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
Samsung 7200rpm disk2tb 24.14 mb/sec25.73 mb/sec 0.280 mb/sec0.299 mb/sec 1.066 mb/sec100 mb/sec 111 mb/sec111 mb/sec
Western Digital Red 5400rpm disk3tb 82.02 mb/sec46.38 mb/sec 1.960 mb/sec0.595 mb/sec 80.8 mb/sec46.6 mb/sec 126 mb/sec131 mb/sec
Intel 710 series SSD300gb 185.6 mb/sec193.9 mb/sec 26.3 mb/sec12.26 mb/sec 27.5 mb/sec26.9 mb/sec 149.9 mb/sec252.0 mb/sec
OCZ Core SSD64gb NA mb/secNA mb/sec NA mb/secNA mb/sec 18 mb/sec21 mb/sec 79 mb/sec116 mb/sec
OCZ Vertex 2 SSD80gb NA mb/secNA mb/sec NA mb/secNA mb/sec 78 mb/sec53 mb/sec 219 mb/sec214 mb/sec
OCZ Vertex 3 SSD (sataII)120gb 172.0 mb/sec233.4 mb/sec 46.11 mb/sec18.95 mb/sec 101 mb/sec99 mb/sec 247 mb/sec279 mb/sec
OCZ Vertex 3 SSD (usb3)(pci-e I)120gb 97.85 mb/sec125.2 mb/sec 32.01 mb/sec16.14 mb/sec 96 mb/sec43 mb/sec 101 mb/sec140 mb/sec
OCZ Vertex 3 SSD (usb3)(pci-e II)120gb 102.0 mb/sec120.1 mb/sec 41.40 mb/sec18.25 mb/sec 48 mb/sec42 mb/sec 103 mb/sec143 mb/sec
OCZ Vertex 4 SSD (sataII)128gb 229.1 mb/sec221.5 mb/sec 51.58 mb/sec20.79 mb/sec 99 mb/sec70 mb/sec 251 mb/sec280 mb/sec
Pny Optima SSD (usb3)(pci-e II)240gb 122.2 mb/sec138.8 mb/sec 11.77 mb/sec11.38 mb/sec 20 mb/sec18 mb/sec 127 mb/sec156 mb/sec
SK Hynix SC215 M232gb N/AN/A 48 mb/sec21 mb/sec 55 mb/sec70 mb/sec 90 mb/sec281 mb/sec

SSD Reliability

I have had 2 OCZ SSD drives fail. When they failed, they just died. They were advertised to have over a million hours MTBF. I am not the only one. Looking at the behardware.com statistics, many SSD drives fail. I am sure there are many reasons, but one reason is sudden power failure. According to This article Intel is the only manufacturer to design their SSDs to have power loss protection. Here is a very interesting article about how Intel tests their SSD drives: The Tech Report.com. Intel clearly do quite a lot of testing. I recommend any computer without an Intel SSD have a UPS. Mine do.

Intel 710 Series, 300gb

I bought my first used SSD. It is an Intel 710, the first Intel enterprise drive that uses MLC (multi level cells). It features 'High Endurance technology MLC'. Intel claims that the High Endurance MLC will sustain 30 times more writes than consumer grade MLC. Before that, all the Intel SSDs used SLC (single level cells). When new it cost around $2000. I bought two used for $50 each. One drive had 329gb written and the otter had 397 gb written according to SMART. Intel has a very good reputation for reliability. The drive is no speed demon, but that is what I expected. It will be replacing a spinning hard drive which will hold operating systems. It will perform much better, use less power, volume, and be more reliable.

A modern hard drive such as the Toshiba TR200 TLC hard drive has 512 gb of unformatted capacity and 480gb of formatted capacity. That is overprovisioning of 6.7%. The Intel 710 300gb has a raw capacity is 586gb which works out to 40% overprovisioning. This is a simple and effective (but expensive) way to increase the number of write cycles for the SSD. Intel specs are Read speed is 270 mb/sec, write speed is 210 mb/sec. Overall, I measured read and write speeds which are reasonably close to spec using an external USB3 enclosure. Intel specs the drive at 38500 read IOPS and 2700 write IOPS. Decent performance for 2011, but not so good for 2017. Using Anvil Storage Utilities, I measured 3k read IOPS and 6K write IOPS with the disk in a USB3 enclosure. I will remeasure when the drive is attached via a SATA port.

OCZ Core SSD 64gb

This is a solid state drive. What that really means is it is a flash drive. How does that differ from a thumb drive? Well, a thumb drive is optimized for low cost and a SSD is optimized for speed. There are 8 flash chips inside the OCZ Core SSD and there is a controller chip that implements 'wear leveling', which tries to keep the number of writes to each memory cell roughly level. If one used the FAT file system, it has a File Allocation Table that gets updated whenever a file on the system gets updated. So the FAT table will see many more writes than the rest of the disk. Modern file systems are more sophisticated than FAT, but the same principle applies.

A solid state disk having no moving parts will tend to be more reliable than a conventional disk with moving parts. Also a conventional disk has what is known as 'seek time' which is the time it takes for the disk head to move from one track to another. A SSD doesn't have a head, so no seek time. A conventional disk has a latency time which is the time it takes for the disk to rotate under the head. A SSD has no disk, and so no latency time. Most SSD's use much less power than conventional disk drives. The OCZ Core uses a maximum of 1.8 watts. In case you go to high altitudes with hard drives, SSD's are unaffected by altitude unlike conventional disks drives. SSD's come in two flavors, SLC (single level cell) which is expensive, fast, and very durable, and MLC (multi level cell) which is less expensive, slower, and about 10 times less durable. With MLC you can store multiple values in a cell, typically 2 bits, which is twice the density of SLC. The OCZ Core is a MLC drive.

Looking at the flash drive summary table, shows the write speed on my old OCZ Core SSD is about 18 times faster for 4k writes than my 2tb 7200 rpm rotating disk. For my OCZ Vertex 4, it is about 90 times faster than my spinning disk. Sequential reads and writes are where rotating disks shine, because there is no seeking. Random access requires seeks which greatly slow down rotating disks.

Thanksgiving 2008, I was able to get a SSD for a reasonable price of $77 after rebate. I am using it for the operation system partitions on my computer. It is a good idea to minimize writing small files to the SSD, as the SSD writes a minimum of 128kb internally whenever you do a write. On linux, simply mount the partition with the noatime switch. On windows, there are a variety of tricks to minimize disk writes. There are good guides on the OCZ web pages for a variety of things that can be done to minimize writes. Here is what I have done. 1) Move the page file to a different disk. 2) Move 'documents and settings' to a different disk. 3) A few registry tweaks. 4) Enable write caching on the SSD. 5) Configure dskcache +p. 6) Disable the indexing service. With these tweaks, my writes are about 15% of my reads of the disk. Since booting today, my reads are 2.34gb and my writes are 228mb (using hddled, a great tool).

I used to use 15k rpm SCSI drives for my OS. They were reasonably cheap, but they made a bunch of noise, and used a lot of power. I have removed my hot-swap SCSI enclosure, SCSI disks and SCSI card, and replaced it with the OCZ SSD. Faster, less power, less noise, more reliable. On my computer, the read speed measured at 118 mbytes/second and the write speed measured at 80 mbytes/second, using atto disk benchmark and a SATA I controller.

Well, 2 months after the warranty expired, the hard drive did also. The failure mode was the hard drive access light would stay lit up, and no data would transfer to or from the drive. The good news was if I shut down the computer for about 10 hours, the disk would work for awhile, long enough to get all the data off of it. I contacted OCZ, and they said they would replace the drive. I didn't hear from them for a week, and I assumed they had shipped the drive. When no drive arrived, I contacted them, and they claimed to have sent me 2 more emails. The thing is, they have a web page that tracks all emails sent for support, and these '2 emails' were not there. After getting back in touch, I returned the broken drive, and they shipped me a new OCZ 64gb onyx SSD. It is newer than my core and supports trim, but it is really, really slow. I am disappointed a drive with a 2 million hour MTBF broke, but at least OCZ replaced it out of warranty.

I was talking with a friend, who had an OCZ Agility 120gb and 60gb drive fail. He also knew of another OCZ Agility 120gb drive that failed. Clearly the 2 million hour MTBF numbers are highly optimistic. 2 million hours is 228 years. Having 4 drives fail within 3 years means the MTBF is closer to 26 thousand hours. When I worked at a company that made an electronic product which was essentially a circuit board. We hired a reliability engineer to determine the MTBF. He calculated it was around 20 thousand hours. We changed a few capacitors, and brought the MTBF to around 80 thousand hours. I think these numbers are far more realistic than SSD or rotating media hard drives which claim over a millions hours of MTBF.

OCZ Vertex 2 SSD 80gb

After my OCZ core drive broke, I decided to get an OCZ Vertex 2 drive. This is a high end consumer MLC drive. I have measured writes of 220 mbytes/second, though they say it can do 250mbytes/second. I measured reads of 228 mbytes/second, though they say it can do 285mbytes/second. OCZ says it will do 50,000 IOPS, which is crazy fast. It is 5 times more than they claim the Agility 2 drive will do. The drive is a little bigger than my core drive. It also cost a bit more. It sure is fast. No problems.

Well, my Vertex 2 drive failed. They symptom was it was not recognized at boot time. Fortunately, it was under warranty. I have ordered a new SSD, and I will be sending this one back. I really wonder where the 2 million hour MTBF comes from. Lets look at some objective data. According to Jeff Atwood, a friend bought eight SSDs and they all failed. Perhaps that small a sample size is unreliable. According to behardware.com, SSDs have return rates (by brand) between 0.45% and 5.02% (during the first year). Here are newer data (in French): hardware.fr 2016 hardware.fr 2015 hardware.fr 2013. Now return rates aren't exactly the same as failure rates, but if someone goes to the trouble to return a SSD, they will have to reinstall all of their software, so I think they really believe that the SSD has failed. Also, not everyone with failed hardware will go to the hassle of returning it. Behardware.com use a minimum sample of 500 sales by brand, and a minimum sample of 100 sales per model. That is a pretty good sample size. According to them, my failed 80 gb OCZ Vertex 2, has a failure rate of 11.76%. Mine lasted 18 months. I am not a MTBF expert, but a year has 6360 hours, so 11.76% in a year is roughly a MTBF of 27,000 hours. OCZ claims a MTBF of 2 million hours. Measured return rate is 74 times less reliable than advertised. The 240gb version of the OCZ Vertex 2 has a failure rate of 15.58%. The OCZ Vertex 2 Pro has an advertised MTBF of 10 million hours, which boggles the mind. I think it is time for a little truth in advertising with MTBF. I do understand that the MTBF time is during the product lifetime, but the published SSD numbers seem to come from the same place as unicorns. I think more realistic numbers are the warranty period. My new SSD has a 5 year warranty, so hopefully it will last a bit longer. Here is a very interesting article about how Intel tests their SSD drives: The Tech Report.com.

OCZ Vertex 3 SSD 120gb

Well, another black friday deal. I bought my first OCZ core drive in 2008. Now, 4 years later I bought the OCZ Vertex 3 120gb drive for $50. It isn't the very fastest drive, but is has a sata III interface, and is rated to do 60k IOPS for random write and 85k IOPS for random read, which is better than the average SSD. I will be using this in a USB3 enclosure as a very fast thumb drive. In theory, USB3 allows a transfer speed of about 500mbytes/second. According to OCZ the drive can write 'up to' 500 mbytes/sec and read 'up to' 550 mbytes/sec. Plugged into my sataII LSI controller, I measured write speeds of up to 136mb/sec and read speeds of up to 143mb/sec, which is quite a bit slower than advertised. That is with firmware 2.22. I updated to firmware 2.25 and did a secure erase. The speed didn't change. I switched to my motherboards native sataII controller, and measured write speeds up to 247 mb/sec and read speeds up to 279 mb/sec. I am sure with a decent sataIII controller, I would measure significantly faster speeds.

Using a cheap USB3 enclosure, I measured write speeds up to 101 mbytes/sec and read speeds up to 140 mbytes/sec. Either this enclosure integrated circuit is really poor, or the USB3 protocol isn't very efficient. I don't think the bottleneck is the OCZ Vertex 3 drive. I suspect either USB3 chips aren't very mature, or I have a really crappy one.

OCZ Vertex 4 SSD 128gb

After my OCZ vertex 2 drive broke, I decided to get an OCZ Vertex 4 drive. This is a high end consumer MLC drive. It has a sata-3 interface, though my computer only has sata-2, limiting the drive to a theoretical speed of 300mb/sec. I have measured writes of 251 mbytes/second. I measured reads of 280 mbytes/second. OCZ says it will do 90,000 IOPS read and 85,000 IOPS write, which is crazy fast. In fact, it is the fastest shipping SSD with a SATA interface today. It cost $100, and claims a MTBF of 2 million hours. More importantly, it has a 5 year warranty, which I might need after my previous 2 OCZ SSDs failed. It sure is fast. No problems yet.

PNY Optima SSD 240gb

Purchased Nov-2014. This is a budget SST. PNY won't even say if it is MLC or TLC. I have it hooked up to the same external USB3 case that my OCZ Vertex 3 was in. Compared to the Vertex 3, the random 512k read and write as well as the max sequential read and write is a bit faster. For sequential and random 4k writes, the PNY gets crushed by the Vertex 3, even though the Vertex 3 was first made around Feb 2011, about 3 1/2 years before the PNY Optima. The only reason to get this drive is it is really inexpensive. Because significantly faster drives are only a few dollars more, there is very little to recommend it. The standard warranty is 1 year, and PNY will extend it by 2 more years if you register it, though that isn't mentioned anywhere in the packaging. Of course, compared to a USB3 flash drive the PNY is significantly faster, and I will be using it as a big USB3 flash drive.

SK Hynix SC215 32gb M2 SSD

This is a M2 SSD that came with my Dell 3040 SFF desktop computer. It is 32mm long. It has very interesting performance characteristics. The maximum write speed maxes out around 90 mbytes/sec and the max read speed around 281 mbytes/sec. This isn't even SATA III speeds. And the write speed is slower than a spinning hard drive. Fortunately, the 4k random speed is much faster than a spinning hard drive. Since it is so small it will be replaced, likely with a 2.5 inch SSD.

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