OCZ Vertex 4 128 GB: Testing Write Performance With Firmware 1.4

When Does The 128 GB Vertex 4 Slow Down?

Our testing indicates that the Vertex 4 128 GB drive's write performance is negatively impacted if sustained write activity extends beyond 50% of its free capacity. When this occurs, sequential and 4 KB random writes above a queue depth of one take a notable hit. When sustained writes extend to less than 50% of available capacity, however, performance is not affected. Therefore, the likelihood that you'd see the Vertex 4's potential suffer depends on the amount of free space you leave and the size of file transfers that occur within that free space.

We presented our findings to OCZ, but the company declined to comment. The inner workings of SSDs are not something that vendors like to dish on. However, OCZ has stated on its forum that the Vertex 4 employs two modes of operation: “performance mode” and “storage mode,” and that the drive is behaving as intended.

Update (6/27/2012): OCZ provided us with an official statement to clarify the behavior if its Vertex 4 armed with the latest firmware. We have not yet confirmed how long it takes the drive to transition back and forth from performance to storage mode and vice versa:

“Prior to the development of firmware 1.4 OCZ has been gathering usage data patterns for quite some time and between selected test case customers and internal SSD usage there are several trends that have repeatedly surfaced that we wanted to address directly with this latest update. One of these is that SSDs, more often than not, have large percentages of unused space. Examples include users leveraging SSDs as boot drives, for their hot data or simply for their more performance oriented applications. In the 1.4 firmware release OCZ leveraged these findings and optimized our garbage collection to provide a significant performance boost to users that fall into this category. Effectively what this means is that drives that are less than half full will enjoy further optimized performance and after crossing more than half full the garbage collection algorithm will re-optimize the drive for maximum efficiency based on a larger data footprint. During this transition there may be a small latency hit, but this is a onetime event, and overall performance quickly improves as the drive is now optimized for the larger amount of storage. OCZ feels that this firmware optimization further enhances the overall SSD experience for our customer base.”

From our observations on a partitioned drive, “storage mode” is encountered when sustained write activity exceeds 50% of the available free space. We can only speculate as to why write performance drops. We suspect that the Vertex 4 uses a very aggressive form of garbage collection that needs available capacity to work effectively, although that only partially explains some of our observations. The only way to avoid “storage mode” is to partition the drive to enable 50% over-provisioning.

While we haven't yet tested the 256 GB Vertex 4, we are led to believe that it doesn't take the same performance hit (though that might be due to the fact that a 256 GB drive is more likely to have more free space than a 128 GB drive). We also believe this issue is related to the customized firmware that OCZ uses and is unrelated to the Marvell controller within.

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  • This is unfortunate. I purchased four of these drives and configured them in RAID 10. I wanted the read performance and the security of knowing I would not have to reinstall everything if a drive failed. I understood I would only have double write performance. But now that I have about 100GB of free space left, I am realizing only single drive write performance. Now I will have to rebuild into a RAID 0 and do regular image backups. :(
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  • What is with these games these vendors are playing with firmware. Sandforce has a trick with compressible data, indelix controllers now expects you to have half your drive empty to get the performance boost?!?

    Why can't you just get the consistent performance like you do on samsung 830's ad crucial m4's, there is nothing wrong with consistency.
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  • Thats too bad.:(
    i was almost on the point of buying a 128GB Vertex4.

    NOT NOW. will wait for the next 1.5 firmware.
    its strange that such type of behavior was documented on Toms only, while multiple other sites have already reviewed this drive with 1.4 fw, giving it a very good rating.

    +1 to Toms review team
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  • so let me get this.. just like vertex III max iops and regular edition there is a performance drop? I sworn this drive had no garbage collection? either way I may buy one, and wait on 1.5. might as well or wait till I see 1.5 firmware.
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  • Man I was really interested in seeing what Indilinx could do, and I've been recommending this drive on all high end builds. I was even thinking of replacing my Intel 320 with one. Guess I'll be sticking with the Crucial M4 and Plextor M3 from now on.
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  • According to OCZ this is the way the firmware for the Vertex4 128GB is designed to work and part of the reason is because of the way MS made the NTFS file system. They say the SSD will only slow down for a short time and then go back up to near normal speeds.

    They also tell me that Tom's Hardware is actually aware of this.

    Read about it here: http://www.ocztechnologyforum.com/forum/showthread.php?102254-Anormal-128GB-Vertex-4-Performance
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  • danielkrThis is unfortunate.

    I read that RAID doesn't support TRIM (never checked beyond that) so I've not bothered with it. Have you done any tests with this?
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  • Todd SauveAccording to OCZ this is the way the firmware for the Vertex4 128GB is designed to work and part of the reason is because of the way MS made the NTFS file system. They say the SSD will only slow down for a short time and then go back up to near normal speeds.


    I am sorry, but there should be never be a slow down, this is ssd, people expect top speed all the time from their drives.
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  • you guys releaize that all ssds slow down when they're half full?
    -4
  • edlivianWhat is with these games these vendors are playing with firmware. Sandforce has a trick with compressible data, indelix controllers now expects you to have half your drive empty to get the performance boost?!?Why can't you just get the consistent performance like you do on samsung 830's ad crucial m4's, there is nothing wrong with consistency.


    Reading Comprehension Fail... Let say you have a 20 Gigabytes of Free Space (The SSD has 512GB total).

    If you try to write a file that is more than 10 GB you'll experience less than optinum performance.

    Note we are talking about Sequential Writing.
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  • KurzReading Comprehension Fail... Let say you have a 20 Gigabytes of Free Space (The SSD has 512GB total).If you try to write a file that is more than 10 GB you'll experience less than optinum performance.Note we are talking about Sequential Writing.


    i understand very well, during the momentary transition from performance mode to storage mode there is a temporary slowdown. How come other vendors don't exhibit this issue, I dont get why ocz would create a problem for themselves, why have two storage modes? Make life simple, make one storage mode.
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  • edliviani understand very well, during the momentary transition from performance mode to storage mode there is a temporary slowdown. How come other vendors don't exhibit this issue, I dont get why ocz would create a problem for themselves, why have two storage modes? Make life simple, make one storage mode.


    Its improbable you'll ever experience this slow down.
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  • waxdartI read that RAID doesn't support TRIM (never checked beyond that) so I've not bothered with it. Have you done any tests with this?

    No testing needed, it simply doesn't work in the overwhelming majority of RAID controllers. Intel produced a beta version of their RST driver that enables RAID 0 support, and there's some really limited support in Linux via dmraid, but that's pretty much it in terms of RAID support and TRIM.
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  • edliviani understand very well, during the momentary transition from performance mode to storage mode there is a temporary slowdown. How come other vendors don't exhibit this issue, I dont get why ocz would create a problem for themselves, why have two storage modes? Make life simple, make one storage mode.

    While OCZ won't fully explain the reasonings behind this (trade secrets and whatnot), it seems that the likely case is to actually improve upon the performance in low-capacity situations.

    As I'm sure you know, as a SSD fills up, it slows down. I'd imagine that the shift, then, is to rework the storage algorithms for the Vtx4 to improve speeds in this more-filled state. If you read the thread Todd Suave posted, you'll get a much better explanation from much smarter people than I.
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  • Firstly, the article frequently uses comments like: "Our Iometer benchmark started with static data occupying 50.4% of the drive." Implying that you filled the drive to 50.4% used, HOWEVER, all your analyzing implies that you actually meant "50.4% free" and so should read "static data occupying 49.6% of the drive."

    Second, the dual storage modes is smart actually. Misleading, but smart. "Performance" mode is obviously MLC being treated as SLC and "Storage" mode is where it's once again treated as MLC. It's a known technique mentioned in research (by storage vendors) to make "cheap" unified product lines by using the same MLC chips in ALL their drives, rather than having two supplies for SLC vs MLC per line. Fast performance by not worrying about the extra bit per cell, but as soon as they have to worry about it, things slow down.
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  • Todd SauveAccording to OCZ this is the way the firmware for the Vertex4 128GB is designed to work and part of the reason is because of the way MS made the NTFS file system. They say the SSD will only slow down for a short time and then go back up to near normal speeds.They also tell me that Tom's Hardware is actually aware of this.Read about it here: http://www.ocztechnologyforum.com/ [...] erformance

    HD Tune Pro doesn't use partitions/formatting at all, but raw writes to the drive, so hiding behind a "It's NTFS, and thus MS fault" does not work in this case.
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  • 444610 said:
    Second, the dual storage modes is smart actually. Misleading, but smart. "Performance" mode is obviously MLC being treated as SLC and "Storage" mode is where it's once again treated as MLC. It's a known technique mentioned in research (by storage vendors) to make "cheap" unified product lines by using the same MLC chips in ALL their drives, rather than having two supplies for SLC vs MLC per line. Fast performance by not worrying about the extra bit per cell, but as soon as they have to worry about it, things slow down.

    Hm. My understanding is that SLC NAND is more expensive, more reliable, and faster, yet is not capable of providing the level of storage MLC can. Does this mean that the transition from 'SLC' mode to MLC mode would be caused by 'SLC' mode running out of capacity? OCZ has stated that the performance-to-storage threshold is different between the 128GB model and 256GB model, which seems a bit conflicting with this theory; there's also the fact that the 512GB model has no performance-mode switch at all.

    OCZ has also stated that this performance dip only occurs when switching between performance and storage, and that the average user wouldn't notice it at all, as the speeds would go back up once it's fully transitioned into storage mode (although it won't be as fast as performance).

    Quote:
    HD Tune Pro doesn't use partitions/formatting at all, but raw writes to the drive, so hiding behind a "It's NTFS, and thus MS fault" does not work in this case.

    The reason that was brought up is exactly that - no user sits there writing in RAW mode. They're saying that it's designed to take advantage of the file system, not that the slows are caused by it.
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  • moussengHm. My understanding is that SLC NAND is more expensive, more reliable, and faster, yet is not capable of providing the level of storage MLC can. Does this mean that the transition from 'SLC' mode to MLC mode would be caused by 'SLC' mode running out of capacity? OCZ has stated that the performance-to-storage threshold is different between the 128GB model and 256GB model, which seems a bit conflicting with this theory; there's also the fact that the 512GB model has no performance-mode switch at all.OCZ has also stated that this performance dip only occurs when switching between performance and storage, and that the average user wouldn't notice it at all, as the speeds would go back up once it's fully transitioned into storage mode (although it won't be as fast as performance).The reason that was brought up is exactly that - no user sits there writing in RAW mode. They're saying that it's designed to take advantage of the file system, not that the slows are caused by it.

    The 128GB drive likely doesn't saturate all I/O channels available to the controller (due to 1 64Gb die per channel likely, or even 2 dies per channel with only half the channels used). The 256GB+ sized drives may not have this dual-mode firmware enabled since they achieve 450+MB/s performance simply due to physical hardware. The performance/storage modes would be a trick used to achieve 256GB+ drive performance, but at 128GB-drive sizes. Also, treating MLC as SLC effectively halves the available space (1 bit per cell instead of 2 bits), thus at 50%, you hit that "out of space in performance mode" threshold, thus forcing the controller into "storage" mode (packing 2 bits per cell, thus having the read-alter-write cycle problems again).

    As for NTFS, no user normally writes in RAW mode, but doing so can simulate dumping a large AVI or somesuch to the drive. Likely they were hoping disk write caching of Windows would save them from micro-writes.
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  • 444610 said:
    Also, treating MLC as SLC effectively halves the available space (1 bit per cell instead of 2 bits), thus at 50%, you hit that "out of space in performance mode" threshold, thus forcing the controller into "storage" mode (packing 2 bits per cell, thus having the read-alter-write cycle problems again).

    This is why I brought up the 256GB model - I haven't seen any specific numbers for it, but it was made apparent that it employs a similar data/drive fill manager as the 128GB:
    Quote:
    The 256's also do this but to a much less degree and at a different fill value.

    While treating MLC as SLC in the 128GB model makes perfect sense, I don't quite see how it'd work out with the 256GB model if it doesn't swap modes at 50%.

    This is really interesting me; I know OCZ is being real protective of their technology behind the Vertex 4, but I would really like to know how this is working.
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  • One more reason to pay a little more and get a Samsung.
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