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vinum vs. DPT smartcacheIV raid - FreeBSD

I have a box with DPT PM2044 SmartCacheIV UW-SCSI PCI cards which can do RAID-5 in hardware, but I'd have to use the DOS volume manager to set up the array. I have heard reports that vinum woudl be faster than using the native card. Is this true? Should I not bother with doing the hardware raid and just go with vinum? The rest of the system is a k6-2 400mhz with 256mb ram (amount might change). I will also have moderate network i/o on the pci bus (obviously). TIA, cowbert -- Peter C. Lai University of Connecticut Dept. of ...

  1. #1

    Default vinum vs. DPT smartcacheIV raid

    I have a box with DPT PM2044 SmartCacheIV UW-SCSI PCI cards which can do
    RAID-5 in hardware, but I'd have to use the DOS volume manager to set up
    the array. I have heard reports that vinum woudl be faster than using the
    native card. Is this true? Should I not bother with doing the hardware raid
    and just go with vinum?

    The rest of the system is a k6-2 400mhz with 256mb ram (amount might change).
    I will also have moderate network i/o on the pci bus (obviously).

    TIA,
    cowbert
    --
    Peter C. Lai
    University of Connecticut
    Dept. of Molecular and Cell Biology
    Yale University School of Medicine
    SenseLab | Research Assistant
    [url]http://cowbert.2y.net/[/url]

    Peter C. Lai Guest

  2. #2

    Default Re: vinum vs. DPT smartcacheIV raid

    > I have a box with DPT PM2044 SmartCacheIV UW-SCSI PCI cards which can do
    > RAID-5 in hardware, but I'd have to use the DOS volume manager to set up
    > the array. I have heard reports that vinum woudl be faster than using the
    > native card. Is this true?
    Doubtful, though I have heard that there are some rare special
    cirstances where software raid can be faster. Given your hardware, you
    will probably not experience those conditions.
    > Should I not bother with doing the hardware
    > raid
    > and just go with vinum?
    Use the hardware RAID, especially if you are going to use a simple RAID
    configuration (like one big RAID-5 virtual disk). Just make sure you have
    some way of figuring out if one of the disks goes bad. Worst case you
    could boot off a DOS floppy once in a while to make sure all the disks are
    still good.
    > The rest of the system is a k6-2 400mhz with 256mb ram (amount might
    > change).
    > I will also have moderate network i/o on the pci bus (obviously).
    --
    Ean Kingston

    E-Mail: ean_AT_hedron_DOT_org
    URL: [url]http://www.hedron.org/[/url]

    Ean Kingston Guest

  3. #3

    Default Re: vinum vs. DPT smartcacheIV raid

    On Wed, Feb 16, 2005 at 09:58:17AM -0500, Ean Kingston wrote:
    >
    > > I have a box with DPT PM2044 SmartCacheIV UW-SCSI PCI cards which can do
    > > RAID-5 in hardware, but I'd have to use the DOS volume manager to set up
    > > the array. I have heard reports that vinum woudl be faster than using the
    > > native card. Is this true?
    >
    > Doubtful, though I have heard that there are some rare special
    > cirstances where software raid can be faster. Given your hardware, you
    > will probably not experience those conditions.
    The reason I asked is because
    [url]http://www.shub-internet.org/brad/FreeBSD/vinum.html[/url]
    suggests vinum can be marginally better than the hardware raid on the
    smartraid range of cards (which have an even faster processor onboard
    than the smartcache range). The CPU platform is more or less comparable.
    Then again it is with old Fbsd, so I don't know how accurate that is.
    >
    > > Should I not bother with doing the hardware
    > > raid
    > > and just go with vinum?
    >
    > Use the hardware RAID, especially if you are going to use a simple RAID
    > configuration (like one big RAID-5 virtual disk). Just make sure you have
    > some way of figuring out if one of the disks goes bad. Worst case you
    > could boot off a DOS floppy once in a while to make sure all the disks are
    > still good.
    >
    > > The rest of the system is a k6-2 400mhz with 256mb ram (amount might
    > > change).
    > > I will also have moderate network i/o on the pci bus (obviously).
    >
    > --
    > Ean Kingston
    >
    > E-Mail: ean_AT_hedron_DOT_org
    > URL: [url]http://www.hedron.org/[/url]
    >
    --
    Peter C. Lai
    University of Connecticut
    Dept. of Molecular and Cell Biology
    Yale University School of Medicine
    SenseLab | Research Assistant
    [url]http://cowbert.2y.net/[/url]

    Peter C. Lai Guest

  4. #4

    Default Re: vinum vs. DPT smartcacheIV raid

    > On Wed, Feb 16, 2005 at 09:58:17AM -0500, Ean Kingston wrote:
    >>
    >> > I have a box with DPT PM2044 SmartCacheIV UW-SCSI PCI cards which can
    >> do
    >> > RAID-5 in hardware, but I'd have to use the DOS volume manager to set
    >> up
    >> > the array. I have heard reports that vinum woudl be faster than using
    >> the
    >> > native card. Is this true?
    >>
    >> Doubtful, though I have heard that there are some rare special
    >> cirstances where software raid can be faster. Given your hardware,
    >> you
    >> will probably not experience those conditions.
    >
    > The reason I asked is because
    > [url]http://www.shub-internet.org/brad/FreeBSD/vinum.html[/url]
    I did not know that. Interesting read.
    > suggests vinum can be marginally better than the hardware raid on the
    > smartraid range of cards (which have an even faster processor onboard
    > than the smartcache range). The CPU platform is more or less comparable.
    > Then again it is with old Fbsd, so I don't know how accurate that is.
    You may have noticed that there were comments about not trusting vinum's
    RAID5 support in that article. If you are using FreeBSD 5.3, the default
    is now gvinum (sort of second generation of vinum). The gvinum tools don't
    give you the ability to create RAID5 virutal disks so if that is what you
    want, you may not want to go with vinum or gvinum.

    Another thing to consider is if you use software RAID and your application
    gets CPU bound, you are going to take a double performance hit (both disk
    and cpu).

    I don't know your situation so it is your call.
    >>
    >> > Should I not bother with doing the hardware
    >> > raid
    >> > and just go with vinum?
    >>
    >> Use the hardware RAID, especially if you are going to use a simple RAID
    >> configuration (like one big RAID-5 virtual disk). Just make sure you
    >> have
    >> some way of figuring out if one of the disks goes bad. Worst case you
    >> could boot off a DOS floppy once in a while to make sure all the disks
    >> are
    >> still good.
    >>
    >> > The rest of the system is a k6-2 400mhz with 256mb ram (amount might
    >> > change).
    >> > I will also have moderate network i/o on the pci bus (obviously).
    >>
    >> --
    >> Ean Kingston
    >>
    >> E-Mail: ean_AT_hedron_DOT_org
    >> URL: [url]http://www.hedron.org/[/url]
    >>
    >
    > --
    > Peter C. Lai
    > University of Connecticut
    > Dept. of Molecular and Cell Biology
    > Yale University School of Medicine
    > SenseLab | Research Assistant
    > [url]http://cowbert.2y.net/[/url]
    >
    > _______________________________________________
    > [email]freebsd-questionsfreebsd.org[/email] mailing list
    > [url]http://lists.freebsd.org/mailman/listinfo/freebsd-questions[/url]
    > To unsubscribe, send any mail to
    > "freebsd-questions-unsubscribefreebsd.org"
    >

    --
    Ean Kingston

    E-Mail: ean_AT_hedron_DOT_org
    URL: [url]http://www.hedron.org/[/url]

    Ean Kingston Guest

  5. #5

    Default Re: vinum vs. DPT smartcacheIV raid

    Peter C. Lai wrote:
    > I have a box with DPT PM2044 SmartCacheIV UW-SCSI PCI cards which can do
    > RAID-5 in hardware, but I'd have to use the DOS volume manager to set up
    > the array. I have heard reports that vinum woudl be faster than using the
    > native card. Is this true? Should I not bother with doing the hardware raid
    > and just go with vinum?
    >
    > The rest of the system is a k6-2 400mhz with 256mb ram (amount might change).
    > I will also have moderate network i/o on the pci bus (obviously).
    I still have one here lingering around somewhere on a shelf. It ran a
    4*1Gb diskarray RAID-5 when 1GB disk where still sort of big. So that is
    how old this card is.

    With that I did have some unplesant experiences with this card:
    - First and most major it seems that you need to have the right version
    firmware in it. Otherwise things might get seriously hossed at
    unexpected times. Just buffers timing out in the middle of the night.
    - The other issue was that my disk where in an external cabinet and once
    the cable came loose. It killed the raid as expected, but it took me a
    long time to find some tools to force the disk up the brute way. Just to
    see if I could recover some of the data.
    And like you say: Al these tools are DOS based.

    Currently I'm running a 4*60Gb ATA RAID5 with old vinum on a 233 MHZ P2,
    256Mb with FBSD 5.1. This ATA just because ATA disk are so much cheaper
    per MB, and I do not need utmost dependability for my 6 PC office.
    I've ordered 4*250Gb ATA disks this week to build a new RAID5, and I'll
    go again for vinum.

    --WjW
    Willem Jan Withagen Guest

  6. #6

    Default Re: vinum vs. DPT smartcacheIV raid

    [Format recovered--see [url]http://www.lemis.com/email/email-format.html][/url]
    > X-Mailer: SquirrelMail/1.4.3a
    This seems to have difficulty wrapping quotes.

    On Wednesday, 16 February 2005 at 10:52:24 -0500, Ean Kingston wrote:
    >
    >> On Wed, Feb 16, 2005 at 09:58:17AM -0500, Ean Kingston wrote:
    >>>
    >>>> I have a box with DPT PM2044 SmartCacheIV UW-SCSI PCI cards which
    >>>> can do RAID-5 in hardware, but I'd have to use the DOS volume
    >>>> manager to set up the array. I have heard reports that vinum
    >>>> woudl be faster than using the native card. Is this true?
    >>>
    >>> Doubtful, though I have heard that there are some rare special
    >>> cirstances where software raid can be faster.
    Recall that there are no real hardware RAID controllers on the
    market. The difference is whether you have a special processor on the
    controller card or not. To determine which is faster, you need to
    compare the hardware on the card and the hardware in the system.
    >> The reason I asked is because
    >> [url]http://www.shub-internet.org/brad/FreeBSD/vinum.html[/url]
    >
    > I did not know that. Interesting read.
    >> suggests vinum can be marginally better than the hardware raid on
    >> the smartraid range of cards (which have an even faster processor
    >> onboard than the smartcache range). The CPU platform is more or
    >> less comparable. Then again it is with old Fbsd, so I don't know
    >> how accurate that is.
    I'd guess that the version of FreeBSD is no particular relevance.
    > You may have noticed that there were comments about not trusting
    > vinum's RAID5 support in that article.
    You'll also note that these claims are in no way substantiated. It's
    word of mouth:
    > However, I still don't trust RAID-5 under vinum (it has had a long
    > and colorful history of surprisingly negative interactions with
    > software that it should not, such as "softupdates"),
    There is in fact no substantiation whatsoever for this claim.
    problems have been reported that suspected either Vinum or soft
    updates, and which were frequently related to neither. We have no
    reason to believe that there was ever the kind of problem he's talking
    about here.
    > and I have not yet had a chance to test vinum under failure mode
    > conditions (where at least one disk of a RAID set has failed).
    I have. It works. There appears to be a bug in reintegrating disks
    with a live file system, so it should be unmounted first.

    (end of quotation).
    > If you are using FreeBSD 5.3, the default is now gvinum (sort of
    > second generation of vinum). The gvinum tools don't give you the
    > ability to create RAID5 virutal disks so if that is what you want,
    > you may not want to go with vinum or gvinum.
    I'm not sure what you mean here. I haven't tried RAID-5 on gvinum,
    but it's the first time I've heard that it's not supported.
    > Another thing to consider is if you use software RAID and your
    > application gets CPU bound, you are going to take a double
    > performance hit (both disk and cpu).
    One or the other. It's a tradeoff.

    [54 lines extraneous text in original removed]

    Greg
    --
    When replying to this message, please copy the original recipients.
    If you don't, I may ignore the reply or reply to the original recipients.
    For more information, see [url]http://www.lemis.com/questions.html[/url]
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    Greg 'groggy' Lehey Guest

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