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  1. #1

    iSCSI SAN vs. GigE Switch

    I'm setting up an iSCSI SAN for 2-3 clients and need some good advice on suitable switch.
    It will be used at home, so think more of a lab environment when it comes to reliability and redundancy than a production environment. Also cost is a big factor, my budget is about $4000 for a switch and a storage server with 1tb raid5/6.
    Usage pattern is workstation-like, since I'm moving the internal HDDs of the workstations (except boot) into the new server.
    Performance should be at least as good as with the previous DAS SATA JBOD, around 40-50MB/s.

    The switch has to have between 16 to 24 ports of GigE because I will run the whole network on it (3 VLANs -> Public/LAN/SAN), besides the SAN I need 12 ports. I planned on having a trunk of 2 GigE run to the storageserver (Intel PRO/1000MT dualport) and single GigE each to the Clients (Intel PRO/1000CT with CSA so no PCI-bottleneck).

    I thougt of a Netgear GSM7224 or GSM7312 (about $850) but I'm still unsure since it's so cheap!
    Evereyone seems to recommend (and use) Cisco or another high-end like Foundry or Force10.
    As a suitable Cisco switch (Catalyst 2970) costs about $3100, I'll have to rethink my plans if there really isn't any way around a switch in this class.

  2. #2
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    The netgears will be fine for your enviroment, you don't need a super-highend layer 3 managed switch for that.
    Last edited by (Stephen); 12-11-2005 at 01:40 PM.

  3. #3
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    You do however need a switch that'll support iSCSI and from a quick Google, the two Netgears mentioned do not appear to support iSCSI. I know the HP28xx line support iSCSI but not having tested their iSCSI performance I can't say how they'd perform.
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  4. #4
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    Karl,

    I think any switch will work, some just have special support.

    There are a number of articles on this, and one of the main iSCSI advantages is "integrates into existing switches" for many that would be switches that pre-date these special iSCSI "enabled" switches.

    http://www.byteandswitch.com/documen...&page_number=6

  5. #5
    [edit:] was taking too much time with posting, no need for the first paragraph in my post [/edit]
    But why?
    AFAIK a layer2 or even a layer3 switch doesn't really know it switches iSCSI traffic (or any other layer5+ traffic). So an iSCSI switch would need to operate on layer5 which is highly unlikely doable in a sub 100'000 box on gigabit wirespeed.
    Maybe I misinterpreted your point?

    The 2824 looks good though, could be a slightly less expensive variant to the Cisco (although still pricey for me at $2600)
    It looks like it's a layer3 switch, can anyone confirm this? (I know the Catalyst 2970 isn't)

  6. #6
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    wagich,

    I think my post probably clarified Karl's statement a bit.

    By 2824 I take it you mean the HP Procurve 2824? It looks to be a limited- layer3 switch from their site.

    But I found it for as little at $1685:
    http://froogle.google.com/froogle_cl...ddr=&scoring=p
    Last edited by (Stephen); 12-11-2005 at 02:30 PM.

  7. #7
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    Yep, the HP is Layer3 if you want it, although I'd not try and push it too far, as at the end of the day it is still a cheap switch (relatively speaking).
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  8. #8
    The HP begins to look like a real option, anyone has performance figures or at least impressions on it?
    $1600's a pretty good deal, although it has to come to Switerland first, so this will be the caveat in online ordering... I'll see.
    [edit2] found it in Switzerland for about $1700, I'm tempted to go with it rather than the Netgear, given it's only $400 more and probably more reliable. HP sells Extreme Networks OEM right? [/edit]

    @JodoHost
    I still don't quite get it. What can a switch possibly do to speed up iSCSI traffic? Prioritize? I can do that with Standard QoS!?

    @KDAWebServices
    I thought that, any other way and there would be no reason to sell those 6U high-perf routers
    But it could come in handy if I need to give a less performance-minded network client access to the storage. (Thinking it will do about 100mbps between VLANs)

    [edit] reread your post Stephen and got the point. It doesn't do anything, just boasts it supports it (as any other $40 switch does) [/edit]
    Last edited by wagich; 12-11-2005 at 02:43 PM.

  9. #9
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    wagich,

    I honestly don't know, it is a marketing gimmick in my opinion

    BTW, I have no experience with those HP's, but I have used the Netgear, not bad but I don't do much more than 2 VLANS on it either.

  10. #10
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    Gah! need more sleep and less DIY. Should have said, yes, it does Basic Layer3 rather than full Layer3. They are a very nice switch for the money and very capable at Layer2, plus you get free NBD advance replacement and lifetime software upgrades - Which can be a real big saving over Brand Cs switches.
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  11. #11
    Well, I think the HP's gonna be it. Thanks for the help!
    Now I only need to find out how exactly basic-layer-3 differs from full-layer-3, as I'm pretty new into this game.

  12. #12
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    Basic Layer3 doesn't support dynamic routing, only static routes, in the case of the HPs, AFAIK it is a maximum of 16 routes (Something is telling me it could be 32 though).
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  13. #13
    I have a similar setup at home but didn't need a fancy layer3 switch to accomplish it. I just bought a cheap "web managed" DELL powerconnect 2716 for $150 which has been more than sufficient for my needs.

    It supports VLANs, LAGs (Link aggregation) and most importantly jumbo frames. Using gigabit without jumbo frames is very hard on the CPU, I saw almost 70% CPU usage on a xeon just transfering files.

    If you really need the fancy routing features or accounting features of a layer3 switch then by all means get it, but for a home setup a layer2 switch and a separate cheap router should be more than sufficient. Save your money and buy some more drives, you'd be surprised how quickly you can fill up 1TB =)

  14. #14
    I'll be definately running Jumboframes - therefore the VLANs
    I'm unsure if I need layer3 routing, eventually i'll cut down there, but as I said before it could come in handy if I need basic cross-VLAN communication.

    Drives won't be a problem. I'll be moving the current 6 200GB drives into the server and eventually add some more later... Altough I know how quickly one uses space, it's incredible

    Thanks for the heads-up on CPU-Utilization, I thought that would be lower... Will be running the server on dual 3ghz then, since it will be doing the iSCSI processing too.

    @roblip
    I'd be interested in performance figures of your setup, if you have any close by?

  15. #15
    Sounds like all questions were answered in this thread. Wagich let us know how things turn out.
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  16. #16
    Well yea, quite. After again a week of thinking (damn, I should've worked then),
    I ordered the hp switch and the server-parts yesterday so I can report on the result after christmas...
    I'm pretty excited and hoping it performs as expected

  17. #17
    Got it all here and the switch up and running.
    Reached my goal of 47mb/s (transfer of single hdd) across the switch between two pro/1000ct's (csa, so no 32bit 33mhz pci limit), CPU load on a 3ghz P4 hovered at around 30% util with and also without jumbo frames. I expect it to get a little better with some tweaks...
    The switch barely got above idle (1-2% cpu load)

    I couldn't yet test the server, as my case seems to have not the right mounting holes for the heatsink. I should've checked, embarassing, I know!

    I'll keep you posted...

  18. #18
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    Quote Originally Posted by wagich
    Got it all here and the switch up and running.
    Reached my goal of 47mb/s (transfer of single hdd) across the switch between two pro/1000ct's (csa, so no 32bit 33mhz pci limit), CPU load on a 3ghz P4 hovered at around 30% util with and also without jumbo frames. I expect it to get a little better with some tweaks...
    The switch barely got above idle (1-2% cpu load)

    I couldn't yet test the server, as my case seems to have not the right mounting holes for the heatsink. I should've checked, embarassing, I know!

    I'll keep you posted...

    What are you using on the server end to do all the iscsi work?

  19. #19
    I'm back from the old year...
    The Servers, switch and firewalls are set-up and everything's running beautifully.
    I'll post detailed experiences later.

    @WireSix
    I tried three different makes of iSCSI software targets (StringBean WinTarget, Starwind and FalconStor), and now pretty much settled on FalconStor (still don't know the price though, but is more expensive than the others I think) since it looks pretty final/stable and the performance is also better than on the other two. (Only tried with a file-device on a RAID5 array, so no hiperf-figures yet)
    [edit:] An article from a german blog (in english) http://www.schrankmonster.de/PermaLi...dc31aba5c.aspx has a short overview and a veery shallow conclusion.[/edit]
    Last edited by wagich; 01-03-2006 at 07:03 PM.

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