Re: Rackmount Serial ATA - Storage

This is a discussion on Re: Rackmount Serial ATA - Storage ; Will wrote: >Does anyone make a rackmountable drive array that is cheap and >uses hotswap Serial ATA drives? I know about the Adaptec >2410SA , but does anyone make a larger external enclosure that >can hold 10+ SATA drives? The ...

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Thread: Re: Rackmount Serial ATA

  1. Re: Rackmount Serial ATA

    Will wrote:
    >Does anyone make a rackmountable drive array that is cheap and
    >uses hotswap Serial ATA drives? I know about the Adaptec
    >2410SA , but does anyone make a larger external enclosure that
    >can hold 10+ SATA drives?


    The question is how do you connect them to the controller if that's in
    another machine? Yes, individual SATA cables can be long enough, but
    it'd be a mess and I really wonder if it's not going to sensitive to
    noise too.

    There are a bunch of FC attached SATA JBOD enclosures, Google for more
    information (that's where I found them). But then you'd need to either
    do software RAID or use a FC RAID controller instead (probably far
    more expensive than those SATA RAID controllers).

    Another option is to get a rack case which combines space for
    motherboard and SATA disks!

    SuperMicro has two 3U cases with space for motherboard and 15 SATA
    disks, that's a nice little "little" file-server there...


    But if you're going for SATA RAID controller and want to run RAID5 you
    should consider which controller you're going to use (RAID1/0/10 puts
    much less load on the controller, so it MIGHT not matter as much).

    Also, with RAID5 you might want a BBU (without it you can choose
    between low RAID5 write performance or unsafe operation), but most of
    the controllers with many channels have this as an option.

    Adaptec has long had a bad performance reputation with their SCSI
    controllers, and there have been complaints of very bad performance of
    their SATA RAID controllers in this group.

    The safe bet is probably 3ware 9500, they've been in the SATA RAID
    segment much longer than the others and been known for performance,
    and the 9500 seems to be quite a bit faster than their older 7500/8500
    controllers. One drawback is that they don't make controllers with
    more than 12 SATA ports, and with the case above 15 (or more) would
    have been better (so either use 12 RAID disks or two controllers).

    I see that LSI logic, the other "classic" provider also has SATA RAID
    controllers, but I've never tried on and to even guess what
    performance they might have I'd first want to know if they're based on
    the AMI or Mylex firmware :-) (they own both and the reputation of
    those two are rather different, though both used to be miles ahead of
    Adaptec).


    >I am interested in RAID enclosures as well, but I would be happy with
    >a JBOD enclosure, and I will handle the RAID management from the host
    >in software.


    I've looked a bit more at that, there are a LOT of options in that
    market, most of them available with FC and SCSI interfaces. But in the
    end we ended up with a SuperMicro machine with the SC933 chassi
    mentioned above (and 3ware 9500S-12 + 9500S-4LP)

    We were mainly looking at Nexsan (various options, 42 SATA/4U and 8 SATA/1U
    is damned impressive) and Infortrend EonStor, but that was mostly due
    to that being what we were being offered.

    Other ones I found with a quick Google: TechnoLand, ExcelMeridian,
    StorCase, Adjile Systems, Maxtronic, Enhance Technology, Promise,
    Peripheral Storage...

    I have a feeling there are much fewer RAID controllers than boxes,
    that much of the difference is in packaging/format. I do wonder how
    many "standard" controllers there are, 2-3 perhaps? (plus several used
    only by the manufacturer themself).

  2. Re: Rackmount Serial ATA

    Torbjorn Lindgren wrote:
    >Will wrote:
    >>Does anyone make a rackmountable drive array that is cheap and
    >>uses hotswap Serial ATA drives? I know about the Adaptec
    >>2410SA , but does anyone make a larger external enclosure that
    >>can hold 10+ SATA drives?

    [..]
    >But if you're going for SATA RAID controller and want to run RAID5 you
    >should consider which controller you're going to use (RAID1/0/10 puts
    >much less load on the controller, so it MIGHT not matter as much).


    http://www.tweakers.net/reviews/557

    Those Areca controllers looks really interresting, and a few others
    are also possible contenders.

    Besides the tested controllers they look at several other alternatives
    at page 15, including Adaptec. It isn't exactly flattering, but seems
    to match what others say about them.

  3. Re: Rackmount Serial ATA

    If you are going the route of PCI cards inside of a Windows or
    Linux box, then what is the best way to just expose those serial
    ATA disks as JBOD to the host OS, and not put RAID in the card?
    If I were going the route of PCI cards I would be tempted to
    manage this through Veritas Volume Manager since it has far more
    capability than anything in the card's firmware.

    --
    Will
    Internet: westes at earthbroadcast.com


    "Torbjorn Lindgren" wrote in message
    news:ytlXd.665694$Zm5.95380@news.easynews.com...
    > Torbjorn Lindgren wrote:
    > >Will wrote:
    > >>Does anyone make a rackmountable drive array that is cheap

    and
    > >>uses hotswap Serial ATA drives? I know about the Adaptec
    > >>2410SA , but does anyone make a larger external enclosure

    that
    > >>can hold 10+ SATA drives?

    > [..]
    > >But if you're going for SATA RAID controller and want to run

    RAID5 you
    > >should consider which controller you're going to use

    (RAID1/0/10 puts
    > >much less load on the controller, so it MIGHT not matter as

    much).
    >
    > http://www.tweakers.net/reviews/557
    >
    > Those Areca controllers looks really interresting, and a few

    others
    > are also possible contenders.
    >
    > Besides the tested controllers they look at several other

    alternatives
    > at page 15, including Adaptec. It isn't exactly flattering, but

    seems
    > to match what others say about them.




  4. Re: Rackmount Serial ATA

    Will wrote:
    >If you are going the route of PCI cards inside of a Windows or
    >Linux box, then what is the best way to just expose those serial
    >ATA disks as JBOD to the host OS, and not put RAID in the card?
    >If I were going the route of PCI cards I would be tempted to
    >manage this through Veritas Volume Manager since it has far more
    >capability than anything in the card's firmware.


    Well, I'd expect that most or all of these cards can run as simple
    JBOD controllers too. Another option is to use multiple "plain"
    controllers, but they tend to top out at 4 SATA disks each, and at
    least some of them you can only have a limited amount of cards! (even
    if you had enough PCI-X/E slots left)

    Another question is how you're going to do with write cacheing, RAID
    1/0 might be able to get decent performance without it, but even with
    that you probably want some kind of BBU (battery backed memory). With
    RAID-5 (and 6) the hit is far worse, and unless you're going to do
    almost no writes you probably need it for RAID-5.

    I suspect that BBU equipped cards should cache writes even to JBOD
    disks, so that might be one option. Another possibility is to try to
    get Veritas to handle it, the question I can't answer is if there are
    hardware that provides this functionality and that Veritas can use
    (and how much work it would to make it work).

    I'd trust many of the full hardware controllers more than I'd trust
    Veritas (their problem IS significantly easier than what Veritas has
    to solve), but others may differ. But Veritas is certainly better than
    doing RAID with the "hostbased" controllers, in this test HighPoint,
    Promise and RAIDCore...

    *If* you don't need a controller with BBU and want to run in JBOD mode
    the card wouldn't have to have a fast CPU, but it would need
    high-speed PCI-X/PCI-E internal and external busses to avoid
    bottlenecks...

    The HighPoint RocketRaid is by far the cheapest of the 8-port card and
    seems to be the obvious candidate if one were to try this (the other
    possible alternative is RAIDCore, but it's much closer to Areca/Tekram
    cards in price, and for this usage it shares many of the limitation
    that the RocketRaid card has)

    If you need cards with BBU that reduces the selection drastically,
    leaving only 3ware 9500S, Areca and LSI. The LSI is a 6-lane
    controller and not a serious contender for this. The 3ware has some
    limitations (including PCI bus speed) so the equally priced Areca (or
    Tekram) is probably the one to check out.

    You mentioned Adaptec 2410SA earlier, I suspect that they may be a bit
    closer to decent performance when used this way (not limited by the
    IOP), but it's not really guaranteed because rumor claims that part of
    their problem is excessive copying as part of the caching, if you use
    the BBU option this could still hurt you..

    Also, they're still limited by their slow internal AND external PCI
    interfaces. There are BBUs for them, but on the other hand they tend
    cost almost as much as the Areca and 3ware 9500S, and even the
    similarly limited 3ware will probably work better.

    But nothing ever beats trying them out with the applications you plan
    to use, but even if you managed to borrow the cards for testing it
    could take quite a bit of time to test all this.

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