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Thread: OCZ Agility SATA 2.0 SSD 120GB

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  1. #1
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    Default OCZ Agility SATA 2.0 SSD 120GB

    Phoronix: OCZ Agility SATA 2.0 SSD 120GB

    Back in May we reviewed the OCZ Vertex SSD, which performed well against a Super Talent SSD and two different rotating mobile HDDs. This OCZ SSD was not exactly cheap but it was not too expensive either and it ended up receiving our Editor's Choice award. Since then, OCZ Technology has introduced the Agility SATA 2.0 Solid-State Drives. The Agility is designed to fill OCZ's mainstream SSD offerings with models up to 120GB in size, MLC flash memory, 64MB cache, and slightly better prices. In this review we are testing out the OCZ Agility 120GB Serial ATA 2.0 SSD, under Ubuntu Linux, of course.

    http://www.phoronix.com/vr.php?view=14096

  2. #2
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    Default Testing Errors

    I have a another theory on why the Agility managed to beat the Vertex.

    Firstly, the Agility series ships with the 1.30 firmware version, which is availible as an update to the Vertex, while your Vertex only was updated to 1.10.

    Secondly, from the article into it sounds like you are using a brand new Agility, but a used (though reformated) Vertex, and it's well known that SSD disks starts to perform slightly worse when they "age".

    These two factors taken tokether is probably the reason that the Agility performed better than the Vertex.

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    Quote Originally Posted by Jonno View Post
    I have a another theory on why the Agility managed to beat the Vertex.

    Firstly, the Agility series ships with the 1.30 firmware version, which is availible as an update to the Vertex, while your Vertex only was updated to 1.10.

    Secondly, from the article into it sounds like you are using a brand new Agility, but a used (though reformated) Vertex, and it's well known that SSD disks starts to perform slightly worse when they "age".

    These two factors taken tokether is probably the reason that the Agility performed better than the Vertex.
    I'm glad someone else noticed! Getting quite fed-up with these half-assed reviews...

    Formatting does NOT reset the disk!

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    Quote Originally Posted by tomm3h View Post
    Formatting does NOT reset the disk!
    Then what would actually reset the disk?
    dd if=/dev/zero of=/dev/sdX ?

  5. #5
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    Quote Originally Posted by tomm3h View Post
    Formatting does NOT reset the disk!
    Quote Originally Posted by Zhick View Post
    Then what would actually reset the disk?
    dd if=/dev/zero of=/dev/sdX ?
    No, as SSD disks differentiate between empty blocks and block with zeroes on it. To write data to an empty block is an easy operation, but to write data to a used block (including a zeroed block) requires the entire erase block (usually consisting of several hundred write blocks) containig it to be erased, and then rewritten again (with new data in that single changed write block). And after that operation all blocks are still used, so the whole procedure has to be done again for the next write block. Write caching will of course help somewhat, but only if multiple writes to the same erase block happens close enough to each other. This is the major factor making random writes hundreds of times slower than sequential writes on SSDs, even though there is no seek latency.

    TRIM is a relatively new addition to the ATA standard that tells the drive that you are not interested in a block any longer, and the drive can go ahead and erase it whenever it has nothing else to do (or just skip rewriting it the next time it is forced to rewrite the erase block). However, hardware vendors don't dare ship a firmware with TRIM support before they have tested that it works in Windows 7 (the first MS OS with TRIM support), and Linux developers don't dare add TRIM support to the kernel untill they have tested that it works on actuall drives. Becouse if you get TRIM wrong, you'll lose user data for sure, and no one likes that. Thus no TRIM support until later this fall.

    Future versions of mkfs.* will hopefully get TRIM support, so that reformating a drive realy does reset the drive to a brand new state, but right now it doesn't, it has no effect on the performance of a drive. Your dd trick, on the other hand, is actually a good way of forcing the drive to a "used" state where it will perfom at it's worst (becouse all blocks have been written to).

    As most disks won't stay brand new for long, "used" performance is actually way more insteresting than "new" performance, so Phoronix should have done that dd trick on both drives before conducting their tests (though I would have used /dev/random just in case the firmware tries to be smart with zeroed blocks, wich isn't likely, but not implausible either). After updating the Vertex firmware to 1.30 of course.

    As stated by others, disk sizes can have a speed impact as well, so comparin the same size would have been more honest, though comparing a 60GB Vertex with an only slightly more expensive 120GB Agility would be interesting as well, if all else was equal. As it stand, this particular benchmark is worse than useless however.

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    Quote Originally Posted by Jonno View Post
    Firstly, the Agility series ships with the 1.30 firmware version, which is availible as an update to the Vertex, while your Vertex only was updated to 1.10.
    Yes.

    Quote Originally Posted by bugmenot View Post
    The reason why 120gb OCZ agility beats 60gb OCZ vertex is because they are different sizes.
    Yes.

    Thanks for pointing out these obvious flaws in this benchmark. Very, very sloppy.

    Also to note is that the 1.30 version of OCZ SSD firmware for the Agility and Vertex introduce a concept called "Garbage Collection". The GC routines kick in when the drive is otherwise idle and is used to organize/collect data on the flash so that it will be able to do it in the most efficient/fastest way possible. The 1.30 firmware has a very early version of GC that can take a lot of idle time to take effect. The next released firmware should be much better in this regard. PCPer has an article which tests an early release of this new firmware which shows how it can help.

    At the very least, both SSDs should have been wiped clean using the tools available from OCZ to make sure both were in the same starting state.

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    Quote Originally Posted by drees View Post
    Also to note is that the 1.30 version of OCZ SSD firmware for the Agility and Vertex introduce a concept called "Garbage Collection". The GC routines kick in when the drive is otherwise idle and is used to organize/collect data on the flash so that it will be able to do it in the most efficient/fastest way possible. The 1.30 firmware has a very early version of GC that can take a lot of idle time to take effect. The next released firmware should be much better in this regard. PCPer has an article which tests an early release of this new firmware which shows how it can help.
    Well, garbage collecting is great, but if all logical blocks are written to neither write combining nor garbage collection will be very usefull, as ther will be no room to manouver in. And without TRIM support all logical blocks will be written to in relatively short order (depending on disk usage of course). Combining this with TRIM support in a future firmware release will be great though. Perhaps even enough to match Intel X-25 M G1 performance, though only time will tell for sure.

    Quote Originally Posted by drees View Post
    At the very least, both SSDs should have been wiped clean using the tools available from OCZ to make sure both were in the same starting state.
    Well, either that or both drives should have been dd:ed to the same "used" starting state. That would also make them comparable, though at lower (and more realisitic) performane.

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    Quote Originally Posted by Jonno View Post
    Well, garbage collecting is great, but if all logical blocks are written to neither write combining nor garbage collection will be very usefull, as ther will be no room to manouver in. And without TRIM support all logical blocks will be written to in relatively short order (depending on disk usage of course). Combining this with TRIM support in a future firmware release will be great though. Perhaps even enough to match Intel X-25 M G1 performance, though only time will tell for sure.
    I don't know - it seems like the PCPer report shows that as long as the drives have enough time to GC, it is enough to regain full write performance. Is it less than optimal? Probably - I'd imagine that with TRIM support less time will be needed for GC.
    Quote Originally Posted by Jonno View Post
    Well, either that or both drives should have been dd:ed to the same "used" starting state. That would also make them comparable, though at lower (and more realisitic) performane.
    Even a dd wipe is not always enough to bring drives to the same state from differing starting states - I'm pretty sure that Anandtech and others found that out as well.

  9. #9
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    That's because a 120G drive has perhaps 130G of blocks available to it.
    This extra space (I don't remember the exact amount of extra space given) allows the drives to write and move blocks about if it needs to combine many blocks to delete them etc, speeding it up.

    When dd-ing a drive a couple of times over, this area will probably get eaten into - while dd-ing a fresh drive only once will leave this spare space alone.

    You also have the firmware storing reference tables etc, and the more that get's messed up, the worse the performance is (another thing I guess 'GC' does on the newer firmwares).

    I've only JUST got 2 30G vertex drives right now (afraid to partition/format them as I'm not 100% sure if I have the 512K alignment correct) - and if these drives are as good as they look then I might get 2 of these and compare - although for a PC you'd want drives around the 120G mark.
    I could do some preliminary file creation / random file copy tests from a ramfs filesystem (so you get rid of that useless read / CPU bound problems) like I did to test my current Core2 (yes, I know - but they're RAID-ed and I'd prefer the nice new Vertex's in my laptops ta :P).

    It strikes me as odd that a Vertex couldn't out-perform a normal rotary drive in a few of these tests - it screams "something wrong here" to me.

    Anyway - PEACE!

    --
    Paul

  10. #10
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    You can make any product look good, depending on what you compare it with. Where is the Intel X-25 E in this head-to-head? Sure it is only 32 Gb, but the other competitors in this race are also not true "competitors" as their capacities are not the same as the reviewed unit.

    When I see disk benchmark comparisons on other sites, they usually report the CPU utilization as well. Why not here?

    It seems to me that the policy is to choose competitors so that the reviewed product always comes out on top. I suppose this makes the manufacturers of the reviewed products happy, but it does not serve the readership well.

    Half of these benchmarks are gratuitous CPU bound tasks where we could all predict the results without looking, but hey, they generate page hits.

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