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  1. #401
    NVIDIA> AMD Fixture Handruin's Avatar
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    Quote Originally Posted by LunarMist View Post
    What is the theory of increasing number of drives vs. % of capacity on max. RAD performance?
    If I have six drives in RAID 6 and add a seventh, will that cause more CPU load from the parity calculations?
    At this point it is about 60% full and would then be about 50% full, but usage will increase in the future.
    There are far too many factors to give a generalized statement on that question. If you're doing mostly large monolithic file transfers, adding more drives could help because you're spreading the load over multiple drives. The parity calculation shouldn't even be noticeable in a healthy array. Are you using software raid or is it done by a raid card? If it's done by a raid card, I wouldn't even worry about going from 6 to 7 drives with regards to parity overhead. I'm running two sets of 10 drives in software raid 6 and it's not even a concern.

  2. #402
    I can't believe I'm a Fixture LunarMist's Avatar
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    Quote Originally Posted by Handruin View Post
    There are far too many factors to give a generalized statement on that question. If you're doing mostly large monolithic file transfers, adding more drives could help because you're spreading the load over multiple drives. The parity calculation shouldn't even be noticeable in a healthy array. Are you using software raid or is it done by a raid card? If it's done by a raid card, I wouldn't even worry about going from 6 to 7 drives with regards to parity overhead. I'm running two sets of 10 drives in software raid 6 and it's not even a concern.
    It is in the Synology with the quad-core Xenon. I suppose it doesn't matter too much.
    --Lunar

  3. #403
    I can't believe I'm a Fixture LunarMist's Avatar
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    Quote Originally Posted by Handruin View Post
    I have no He drives to compare to so I'm unable to give feedback.
    But you do like them and would buy more?
    --Lunar

  4. #404
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    Quote Originally Posted by LunarMist View Post
    What is the theory of increasing number of drives vs. % of capacity on max. RAD performance?
    If I have six drives in RAID 6 and add a seventh, will that cause more CPU load from the parity calculations?
    At this point it is about 60% full and would then be about 50% full, but usage will increase in the future.
    Why would more drives cause the parity calculation to be more complex?

  5. #405
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    Quote Originally Posted by Stereodude View Post
    Why would more drives cause the parity calculation to be more complex?
    I have no idea. So what are the parameters?
    --Lunar

  6. #406
    Storage? I am Storage! Howell's Avatar
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    Quote Originally Posted by LunarMist View Post
    What is the theory of increasing number of drives vs. % of capacity on max. RAD performance?
    If I have six drives in RAID 6 and add a seventh, will that cause more CPU load from the parity calculations?
    At this point it is about 60% full and would then be about 50% full, but usage will increase in the future.
    It would add no more load to parity calculations and would spread the work over more spindles. Win.

  7. #407
    I can't believe I'm a Fixture LunarMist's Avatar
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    Thanks. I may do that over the winter.
    --Lunar

  8. #408
    I can't believe I'm a Fixture LunarMist's Avatar
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    Synology has a DX1215 expansion unit for the DS3617xs, etc. that connects by a fairly short inifiband cable.
    Does anyone have experience with this type of cable or expanding the NAS? I would create a separate array of lower speed drives so the impact of the external interface is unimportant, but I would like to run a 2m cable between the NAS and expansion box. Thanks.
    --Lunar

  9. #409
    NVIDIA> AMD Fixture Handruin's Avatar
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    If it's infiniband the cable might conform to an SFP+ or QSFP+ depending on the speed. Those connection types are a standard and depending on how far you need to run a cable you will have shorter limits using DAC copper cable vs going with fiber optics.

    Can you provide the specs for the Infiniband interface on the DX1215?

  10. #410
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    I tried to look it up and it does not appear to be an SFP+ connection. It's some kind of Infiniband sata x4 cable that I'm unfamiliar with.

  11. #411
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    Quote Originally Posted by Handruin View Post
    I tried to look it up and it does not appear to be an SFP+ connection. It's some kind of Infiniband sata x4 cable that I'm unfamiliar with.
    It appears to be an SFF-8470, a trapezoidal type of connector. I'm not familiar with it, only SFF-8087 and SFF-8088.
    https://www.servethehome.com/wp-cont...Connectors.jpg
    https://www.servethehome.com/sas-sat...ce-connectors/

    I suppose I can order and take a chance.
    Last edited by Handruin; 01-13-2018 at 01:03 PM.
    --Lunar

  12. #412
    I can't believe I'm a Fixture LunarMist's Avatar
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    I found this fanless switch for 10GbE. It has only four SFP+ ports, but noiseless is nice.
    --Lunar

  13. #413
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    Quote Originally Posted by LunarMist View Post
    I found this fanless switch for 10GbE. It has only four SFP+ ports, but noiseless is nice.
    MikroTik has one even cheaper (under $150) if you can live with 2 SFP+ ports.

    https://mikrotik.com/product/CSS326-24G-2SplusRM

  14. #414
    I can't believe I'm a Fixture LunarMist's Avatar
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    What is the point of two ports for a single user?
    --Lunar

  15. #415
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    Quote Originally Posted by LunarMist View Post
    What is the point of two ports for a single user?
    Uh, maybe you only have two 10gb devices.

  16. #416
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    Quote Originally Posted by Stereodude View Post
    Uh, maybe you only have two 10gb devices.
    Then what would be the need for a switch? The NAS have GbE ports as well. I'm sure some normal single users would find a use, but it wouldn't work for me.
    Of course in a datacenter the incoming 10GbE is distributed to the groups or individuals of gBE users.
    --Lunar

  17. #417
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    It's useful if you have multiple computers with 1Gb connections that connect to one or two NAS devices with 10Gb connections assuming the NAS is capable of dealing with the IO.

  18. #418
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    Quote Originally Posted by Stereodude View Post
    MikroTik has one even cheaper (under $150) if you can live with 2 SFP+ ports.

    https://mikrotik.com/product/CSS326-24G-2SplusRM
    IIRC Coug mentioned that Lithuanian brand a while ago. I cannot find any for sale online in the US.
    --Lunar

  19. #419
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    I found one at Amazon for $132 in like 10 seconds of searching.

  20. #420
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    Quote Originally Posted by LunarMist View Post
    Then what would be the need for a switch? The NAS have GbE ports as well.
    Maybe the two systems with 10gb need to talk to each other over a very high bandwidth link and still talk to other systems and you don't want the headache of connecting the two 10gb systems directly to each other and also to a 1gbE switch and have to manage which interface they use for transferring data in every program / protocol.

  21. #421
    I can't believe I'm a Fixture LunarMist's Avatar
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    I'm sure there are a lot of possibilities, but I'd rather have more ports. Four would be the least, but eight would be nice for future proofing.
    I really should be buying a new monitor before the NAS updrages.
    --Lunar

  22. #422
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    Quote Originally Posted by LunarMist View Post
    I'm sure there are a lot of possibilities, but I'd rather have more ports. Four would be the least, but eight would be nice for future proofing.
    I really should be buying a new monitor before the NAS updrages.
    For me, I only need two SPF+ once I initially go 10gb. The MicroTik would work. Sure, it doesn't have any room for expansion, but it's cheap enough that by the time I need to add a 3rd 10gb computer (not anytime soon) there will likely be other cheap fanless switch options with more SPF+ ports that cost likely less than the TP-Link.

  23. #423
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    I have two computers and two NAS with SFP+ at this point, so the main reason for a switch would be to use more NAS or more computers.
    I'm not sure about the future of that interface.
    --Lunar

  24. #424
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    I doubt you will see SFP+ interface go away any time soon. It's quite versatile by allowing you to select direct attached copper cables or to go to fiber optic for longer distances and improved signal to noise because there is no electrostatic interference. Performance, latency, and power consumption is also better at the receptacle ends when compared to an RJ45 connection type.

  25. #425
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    Quote Originally Posted by Handruin View Post
    I doubt you will see SFP+ interface go away any time soon. It's quite versatile by allowing you to select direct attached copper cables or to go to fiber optic for longer distances and improved signal to noise because there is no electrostatic interference. Performance, latency, and power consumption is also better at the receptacle ends when compared to an RJ45 connection type.
    Thanks. I decided on the cheap route and added the 5-pack USB to the backup NAS.
    --Lunar

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