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Thread: How RAID can give your hard drives SSD-like performance

  1. #31

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    Quote Originally Posted by AndrewAlston View Post
    Bottom of the range ssd vs top of the range ssd makes no difference - they are both SATA-3 which is 6gigabit a second - and a 12gigabit a second raid controller is going to outrun that - period
    lol what? since when is bottom of the range adata ssd equal to a top of the range samsung ssd? share that **** youre smoking.

    since you are throwing in a 12gbps controller, why not throw in a pcie ssd or some nonsense.

    wtf kind of comparisons are you making hahaha

    fact is ssd is faster - periods


    edit: on top of that the controller speeds differ too, like marvell vs intel. some people raid their ssd but their controller cannot go faster than if it was a single drive anyway
    Last edited by access; 18-04-2018 at 05:59 PM.

  2. #32

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    Quote Originally Posted by AndrewAlston View Post
    Bottom of the range ssd vs top of the range ssd makes no difference - they are both SATA-3 which is 6gigabit a second - and a 12gigabit a second raid controller is going to outrun that - period
    And a 20Gbps SSD M.2 Raid controller will outrun a 12Gbps Raid controller lol.
    http://www.highpoint-tech.com/USA_ne...76x-rr274x.htm

  3. #33

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    Quote Originally Posted by AndrewAlston View Post
    Figured this would be of interest..

    These are tests I just ran on one of my machines -

    First test - the Samsung 512gig m.2 nvme drive:

    Attachment 515535

    Note - its a very consistent result - and the random access speeds are *extremely* fast - again though - thats not limited by 6gig SATA speeds.

    Second result - this was done against a 8 x 6TB HGST based raid on an Avago 9361-16i Raid controller running RAID-6

    Attachment 515539

    Random access times are way way up here - but on the sequential read - I'm still outrunning any standard SSD because I'm sitting at 7.4gigabit average there - higher than the port speed available to an SSD (and actually bursting higher than the m.2 drive)

    Third result - this was done against another array on the same controller - this time on 8 x 10TB HGST 7200 RPM drives - these drives are newer and have MUCH more built in cache on the drives

    Attachment 515541

    You'll notice the random access speeds are slightly better than the second test - at 7.7ms - but the average speed is pretty consistent with the previous test.
    Do us a fav. Cut out the sequential read tests. That's useless info mostly. Please post 4K random read / write tests - this is how drives behave in an OS... unless you're using them for once off storage as in a backup device that is archived...

  4. #34

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    The only time this is true...is if you are RAIDing SSD's.

    Otherwise it's all bull**** in real world usage.

  5. #35
    Group Head of IP Strategy – Liquid Telecommunications
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    Quote Originally Posted by CataclysmZA View Post
    Two Samsung 850 EVO 500GB drives in RAID 0 will outrun your array for a fraction of the price - and that's on SATA 3 via Intel or AMD's chipsets.



    International brand, founded in London. They've been around since 2009 They have an e-Commerce product that they license to franchisees globally, which basically works like Esquire's reseller service.
    Actually - thats not accurate - for two reasons.

    Firstly - the performance is pretty similar (tomorrow I'll paste you a test, I've got anotehr machine with those as boot drives, they peak at pretty much the same point and sustained is also reasonably similar)

    Secondly - on the price point - as I stated earlier - raid makes sense on large disks - if you had to try and put enough samsung EVO's in place to replicate the speed - it would cost you one hell of a lot more. Your price per gig on SSD is massive - a 4TB SSD will still cost you R20k+ - a 10TB disk can be had for R6k odd - raid 8 x 10, you're in around 50 grand at end up with similar performance with 60 odd TB active after raid loss - take 8 x 4 SSD's you get 32 TB, and have spent 160 grand - and if you don't raid them you don't have the redundancy either - if you do - you're down to 24TB of space - or R6.6k per TB - vs probably a R1k per TB on the 12gig raid - so on large capacity systems - the raid is cheaper - WAY cheaper - for the same performance.

  6. #36
    Group Head of IP Strategy – Liquid Telecommunications
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    Quote Originally Posted by manicminer View Post
    And a 20Gbps SSD M.2 Raid controller will outrun a 12Gbps Raid controller lol.
    http://www.highpoint-tech.com/USA_ne...76x-rr274x.htm
    Heh agreed - Please note what I said about M.2 drives - but good luck getting high capacity M.2 and paying for it

  7. #37

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    Quote Originally Posted by AndrewAlston View Post
    Heh agreed - Please note what I said about M.2 drives - but good luck getting high capacity M.2 and paying for it
    We still want to see the results of your raid 4k random tests please

  8. #38

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    Quote Originally Posted by AndrewAlston View Post
    Firstly - the performance is pretty similar (tomorrow I'll paste you a test, I've got anotehr machine with those as boot drives, they peak at pretty much the same point and sustained is also reasonably similar)
    I know they'll be similar, but the two SSDs in RAID will edge out a win compared to your RAID array. Sustained speeds will be more consistent, but your latencies will be far lower. Sure, you can burst higher than what a 950 Pro can manage, but that's a pointless statistic considering you can't maintain that speed for very long.

    Quote Originally Posted by AndrewAlston View Post
    Secondly - on the price point - as I stated earlier - raid makes sense on large disks - if you had to try and put enough samsung EVO's in place to replicate the speed - it would cost you one hell of a lot more.
    I'm assuming that you meant size here, and not speed. On size, we are in agreement - there's no way you're building a 32TB HDD array and a 32TB SSD array for the same price. Especially when you're dealing with stuff that gets an "enterprise" label slapped on it along with the firmware to go with it. But you're never going to get anything close to the same performance out of them. Hook up eight SATA SSDs to that MR9361 and watch it bottleneck because there aren't enough PCIe lanes for all the bandwidth you have on tap.

    Dividing the average read speed in your best result - 981.6MB/s - gives you a per-drive average of 122.7MB/s, and a top burst speed of 183.2MB/s. It's decent, but there are drives available today using helium that I recall approaching 200MB/s pretty consistently. WD's new DC HC530 is rated for 267MB/s using PMR with helium, but that's only at the start of the disk's readable sectors, slowing down as the head moves further out the platter.
    Last edited by CataclysmZA; 19-04-2018 at 02:08 PM.

  9. #39

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    Quote Originally Posted by CataclysmZA View Post
    /snip
    You should check out the price of Mushkin drives on Wootware...
    I just did they are well priced, but not sure if I trust the name.
    I spent a lot of money on booze, birds and fast cars. The rest I just squandered - George Best

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