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most affordable 24pt SAS2 Expander cards? (w/cables, not chassis/backplane)

Discussion in 'FreeBSD, ZFSguru, and FreeNAS' started by Twice_Shy, Feb 15, 2017 at 1:53 AM.

  1. Twice_Shy

    Twice_Shy Member

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    I'm specifically looking for an SAS2 Expander for SnapRAID right now - but the plan is in the future to reuse the same hardware under FreeNAS ZFS in the future so i'm asking here, since it sounds like anything under linux should work fine for snapRAID anyway. I'm hoping if it has BSD support it also has linux support and if I understand Expanders it shouldn't even matter on the software/OS at all.

    I am looking for SAS2 Expanders - I looked through the Buying Guides here, and they talk about good HBA's and such, but I didn't see a mention of what Expanders to use. I dont mind Expanders which require PCI or PCIe slots for power, or even slaving some old motherboard to provide power for it if needed as long as the per-port cost is substantially lower. (and prefer the more available PCIe x1 by now of course, or/and wonder if one of those bitcoin risers x1 to x16 could be used for cards that seem to want to sit in an x4 or x8 slot - I assumed there was the same power feed to all cards regardless of lanes afterall) Of course something that stands alone is more flexible/not needing a motherboard to power it.

    I don't need full hot swap chassis with built in cordless backplane whatever - i'm fine connecting cables in existing cases for now. Just need the Expander which will let me hook up drives in ATX cases and i'm happy.

    I see on ebay 24 port SAS expanders as low as $50 - it's not clear if they are SAS1 or SAS2 but I assume SAS1, though some claim 6gbps speed - so i'm not sure if that's the only thing to search for as a term. I don't know whether there are any concern with brands - should an HP or Dell SAS Expander work perfectly fine in anything else? (my assumption is they need no drivers so should) Any to avoid/known problems? Any widely known as reliable?
     
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  2. i386

    i386 Active Member

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    That's becuase many use server chassis where the expander is on the backplane and not an add on card.

    For more information about the sas2 HP expander read this thread HP SAS Expander Wiki

    Personally I would use one of the Intel expander (with an LSI chip) add on cards becuase they can use pcie or molex 4pin for power.
     
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  3. Twice_Shy

    Twice_Shy Member

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    Yes, i'm aware most are built into backplanes. The used chassis+backplanes are costing more than i'd like and i'd rather use my own chassis for now to include 5.25 opticals and such too.

    Most of the cards I see on ebay seem to be SAS1 HP Expander cards. I was wondering if an SAS1 expander can be used with an SAS2 HBA just with the limits of SAS1 speed - or if it would also share the problem with 2TB hard drives and such. I could still saturate 1gigE for now and upgrade when prices come down later. (or it could go in my backup system since I dont have the money to build two 'full speed' systems right now if something were to happen to the main one, and just swap over drive cables if there's a problem)

    Which Intel Expander would I search for? I also see some maker called Chenbro/wondering if anyone besides Intel or HP is worth considering.
     
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    Last edited: Feb 15, 2017 at 2:50 AM
  4. rubylaser

    rubylaser Active Member

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    #4
  5. i386

    i386 Active Member

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    Expanders are "active", my guess is that they share the same problems.

    My recommendation is the Intel RES2SV240.

    Chenbro uses LSI expander chips (LSI SASIIX28/SASIIX36).
     
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  6. Tom5051

    Tom5051 Member

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    You don't mention what RAID controller you intend to hook the expander up to.
    Expanders will only work when connected to a RAID controller that supports expanders.
    Since you're talking about snapraid, makes me wonder if you are talking about software raid. In which case an expander will not work, you'd need a sata add-in card with lots of ports.

    The 24 port sas expander will only support 16 drives, the 36 port will only support 24 drives.
    The other ports are for connecting to the controller and daisy chaining to another sas expander.
     
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  7. i386

    i386 Active Member

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    SAS HBAs support expanders.
     
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  8. Tom5051

    Tom5051 Member

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    Not all of them do actually and quite a few brands are fussy with the brand of expander.
    OP makes no mention of HBA so what is your point exactly?
     
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  9. Aestr

    Aestr Active Member

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    If he needs a lot of ports for software RAID as mentioned there are many SAS HBAs that will work just fine with an expander. Whether it's better to use multiple HBAs vs one and an expander comes down to price, free pci-e slots and performance requirements.

    The 24 port Intel expander mentioned above that is always very popular due to availability and price supports 20 drives not 16.


    Sent from my iPhone using Tapatalk
     
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  10. markarr

    markarr Active Member

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    and most of those brands can be reflashed to the base LSI firmware which will work with both the intel and chenbro expanders. The point he was trying to make is that an sas hba in IT mode with an expander can do the same thing as a SATA cards in software raid. There are very few manufacturers of SAS chips so if you have the chip from the same generation and manufacturer it will work (fw flash may be needed).

    I would also recommend the intel expander, I had it behind a reflashed ibm 1015 and had no issues using both ZFS and snapRAID.
     
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  11. rubylaser

    rubylaser Active Member

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    #11
  12. whitey

    whitey Moderator

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    LSI HBA (2008/2308/3008 variant) paired w/ a Intel RES2SV240 is what you want for a 'big ole box of JBOD/sw raid' setup.
     
    #12

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