RAID1 - what happens if your motherboard RAID controller dies? - Storage

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Thread: RAID1 - what happens if your motherboard RAID controller dies?

  1. RAID1 - what happens if your motherboard RAID controller dies?

    I have a motherboard with a hardware RAID controller built in and I
    intend to set up two identical drives in RAID 1 configuration. My
    worry is how I would go about recovering the data from either drive if
    my motherboard goes down. I assume that you can't just plug one of the
    drives in to another motherboard and expect it to be read by a normal
    SATA2 (in my case) connection. So how would I recover the data in this
    worst case condition?

  2. Re: RAID1 - what happens if your motherboard RAID controller dies?

    On May 22, 4:25*pm, clangers_sn...@yahoo.co.uk wrote:
    > I have a motherboard with a hardware RAID controller built in and I
    > intend to set up two identical drives in RAID 1 configuration. My
    > worry is how I would go about recovering the data from either drive if
    > my motherboard goes down. I assume that you can't just plug one of the
    > drives in to another motherboard and expect it to be read by a normal
    > SATA2 (in my case) connection. So how would I recover the data in this
    > worst case condition?


    You would need to replace the motherboard anyways, and that would fix
    the problem (assuming the motherboard hasn't been discontinued).

  3. Re: RAID1 - what happens if your motherboard RAID controller dies?

    clangers_snout@yahoo.co.uk wrote:
    > I have a motherboard with a hardware RAID controller built in and I
    > intend to set up two identical drives in RAID 1 configuration. My
    > worry is how I would go about recovering the data from either drive if
    > my motherboard goes down. I assume that you can't just plug one of the
    > drives in to another motherboard and expect it to be read by a normal
    > SATA2 (in my case) connection. So how would I recover the data in this
    > worst case condition?


    It depends entirely on the mobo/controller(s) in question. For example, I
    have a customer whose MSI socket 754 mobo failed, this had 2 SATA srives in
    Raid1. I got him a new board, an Intel P35 based one, so different kit all
    round. I attached one of the drives in normal mode and it was read
    immediately, just needed to change the drivers and we were up and running. I
    then just added the 2ns drive back and rebuilt the Raid.
    This does not mean however that it will work this way every time, you just
    have to suck it and see sometimes.
    --
    SteveH



  4. Re: RAID1 - what happens if your motherboard RAID controller dies?

    clangers_snout@yahoo.co.uk wrote in news:0695512c-c9b3-4272-909e-72819fad4545@d45g2000hsc.googlegroups.com
    > I have a motherboard with a hardware RAID controller built in and I
    > intend to set up two identical drives in RAID 1 configuration. My
    > worry is how I would go about recovering the data from either drive if
    > my motherboard goes down.


    > I assume


    You do? What is your assumption based on?

    > that you can't just plug one of the drives in to another motherboard
    > and expect it to be read by a normal SATA2 (in my case) connection.


    No? Why not? Have you tried?

    > So how would I recover the data in this worst case condition?


    Not, based on your assumption.

    How does the word "backup" sound to you?

  5. Re: RAID1 - what happens if your motherboard RAID controller dies?

    In comp.sys.ibm.pc.hardware.storage SteveH wrote:
    > clangers_snout@yahoo.co.uk wrote:
    >> I have a motherboard with a hardware RAID controller built in and I
    >> intend to set up two identical drives in RAID 1 configuration. My
    >> worry is how I would go about recovering the data from either drive if
    >> my motherboard goes down. I assume that you can't just plug one of the
    >> drives in to another motherboard and expect it to be read by a normal
    >> SATA2 (in my case) connection. So how would I recover the data in this
    >> worst case condition?


    > It depends entirely on the mobo/controller(s) in question. For example, I
    > have a customer whose MSI socket 754 mobo failed, this had 2 SATA srives in
    > Raid1. I got him a new board, an Intel P35 based one, so different kit all
    > round. I attached one of the drives in normal mode and it was read
    > immediately, just needed to change the drivers and we were up and running. I
    > then just added the 2ns drive back and rebuilt the Raid.
    > This does not mean however that it will work this way every time, you just
    > have to suck it and see sometimes.


    The issue here is where the RAID stores its metadata. If in EEPROM,
    you are fine. If on the end of the disk, you are fine as well.
    If at the beginning of the disk, it gets difficult.

    But, true, for RAID1 you may get lucky. I would advise you to
    try removing a disk and reading it non-raided in a different
    computer. If that works, it should also work in the future ;-)

    Arno



  6. Re: RAID1 - what happens if your motherboard RAID controller dies?

    On or about Thu, 22 May 2008 13:25:45 -0700 (PDT) did
    clangers_snout@yahoo.co.uk dribble thusly:

    >I have a motherboard with a hardware RAID controller built in and I
    >intend to set up two identical drives in RAID 1 configuration. My
    >worry is how I would go about recovering the data from either drive if
    >my motherboard goes down. I assume that you can't just plug one of the
    >drives in to another motherboard and expect it to be read by a normal
    >SATA2 (in my case) connection. So how would I recover the data in this
    >worst case condition?


    You assume incorrectly, in every RAID1 setup I've seen. Each member can be
    accessed as a stand-alone drive if necessary, on a normal controller.

    Whatever on-disc configuration information there is resides outside the normal
    disc layout (partition, LVM, whatever).

  7. Re: RAID1 - what happens if your motherboard RAID controller dies?

    Arno Wagner wrote in news:69medlF34hpilU1@mid.individual.net
    > In comp.sys.ibm.pc.hardware.storage SteveH wrote:
    > > clangers_snout@yahoo.co.uk wrote:
    > > > I have a motherboard with a hardware RAID controller built in and I
    > > > intend to set up two identical drives in RAID 1 configuration. My
    > > > worry is how I would go about recovering the data from either drive if
    > > > my motherboard goes down. I assume that you can't just plug one of the
    > > > drives in to another motherboard and expect it to be read by a normal
    > > > SATA2 (in my case) connection. So how would I recover the data in this
    > > > worst case condition?

    >
    > > It depends entirely on the mobo/controller(s) in question. For example, I
    > > have a customer whose MSI socket 754 mobo failed, this had 2 SATA srives
    > > in Raid1. I got him a new board, an Intel P35 based one, so different kit all
    > > round. I attached one of the drives in normal mode and it was read
    > > immediately, just needed to change the drivers and we were up and running.
    > > I then just added the 2ns drive back and rebuilt the Raid.
    > > This does not mean however that it will work this way every time, you just
    > > have to suck it and see sometimes.

    >
    > The issue here is where the RAID stores its metadata. If in EEPROM,
    > you are fine. If on the end of the disk, you are fine as well.


    > If at the beginning of the disk, it gets difficult.


    Difficult, babblebot?

    >
    > But, true, for RAID1 you may get lucky.


    > *I would advise you*


    Don't you love the sound of that.
    He get's corrected yet immediately starts to advise again.

    Maybe this time his advice is better, no?

    > to try removing a disk and reading it non-raided in a different computer.


    > If that works, it should also work in the future ;-)


    Or not.
    Babblebot's way of saying he didn't understand at all what previous poster was saying

    >
    > Arno


  8. Re: RAID1 - what happens if your motherboard RAID controller dies?

    Squeeze wrote:
    >
    >> to try removing a disk and reading it non-raided in a different
    >> computer.

    >
    >> If that works, it should also work in the future ;-)

    >
    > Or not.
    > Babblebot's way of saying he didn't understand at all what previous
    > poster was saying
    >


    I was gonna say, that's what I said, more or less.
    --
    SteveH



  9. Re: RAID1 - what happens if your motherboard RAID controller dies?

    On Thu, 22 May 2008 13:25:45 -0700 (PDT),
    clangers_snout@yahoo.co.uk wrote:

    >I have a motherboard with a hardware RAID controller built in and I
    >intend to set up two identical drives in RAID 1 configuration. My
    >worry is how I would go about recovering the data from either drive if
    >my motherboard goes down. I assume that you can't just plug one of the
    >drives in to another motherboard and expect it to be read by a normal
    >SATA2 (in my case) connection. So how would I recover the data in this
    >worst case condition?


    Unlike other RAID levels, a RAID1 does not need metadata to
    work and in fact can be made on any normal controller by
    taking a drive that was not a member of any raid array,
    hooking it up to the controller, then telling the controller
    to dupe that onto a second drive.

    Because it's RAID1 you should be able to pull either drive
    (assuming both are still working, that whatever killed the
    motherboard did not effect the drive(s)), install in any
    other standard SATA150 or 300 system and have all the data
    intact.

    IF you had been talking about a RAID0 instead, you'd need to
    connect them to a compatible controller, the safest bet is
    to buy another motherboard with exact same southbridge chip
    or discrete RAID controller chip - depending on which chip
    gives it the raid functionality... usually on consumer gear
    today it's the southbridge like an Intel ICH9R for example.
    However, it is possible that with the Intel Matrix RAID you
    might be able to set up some kind of RAID that is not
    supported by separate controllers, I am only speaking of a
    traditional RAID1 above where you have the array using the
    entirety of both drives, not trying to regain excess space
    on one if one is larger than the other, but once you had an
    array set up it would not be a problem to put multiple
    partitions on it.

    Ultimately the safest bet is to test your recovery strategy.
    Put some test data on the array, then power off pull drive
    and put in another system to confirm you have access to it.
    It should also be said that an online RAID1 isn't really a
    substitute for a removable/removed backup of the data since
    a power surge, PSU failure, virus or whatever could equally
    wipe out drives and/or data simultaneously.

  10. Re: RAID1 - what happens if your motherboard RAID controller dies?

    SteveH wrote in news:LKuZj.8101$DZ6.6937@text.news.virginmedia.com
    > Squeeze wrote:


    Some context restored:
    > > This does not mean however that it will work this way every time, you just
    > > have to suck it and see sometimes


    > >
    > > > to try removing a disk and reading it non-raided in a different computer.

    > >
    > > > If that works, it should also work in the future ;-)

    > >
    > > Or not.
    > > Babblebot's way of saying he didn't understand at all what previous
    > > poster was saying
    > >


    > I was gonna say, that's what I said,


    Why would the babblebot repeat what you said?

    > more or less.


    It's obviously gonna work in that particular computer that he would
    have checked it in but that doesn't mean it will work in any new
    computer he might buy when/if the actual incident is going to happen.
    By the time it happens computers without RAID capability may not be
    available anymore. RAID controllers may well check in specific places
    for any evidence of previous raid implementation and refuse to accept
    it when its not their own, even if you want to use it as non-raided.
    To avoid such unwanted behaviour the RAID capability must be able
    to be switched off entirely.

    Like you said, it depends. That's not what the babblebot said.

    If want to be sure, have backups.

  11. Re: RAID1 - what happens if your motherboard RAID controller dies?

    On Sat, 24 May 2008 00:09:54 +0100, "Squeeze"
    wrote:

    >SteveH wrote in news:LKuZj.8101$DZ6.6937@text.news.virginmedia.com
    >> Squeeze wrote:

    >
    >Some context restored:
    >> > This does not mean however that it will work this way every time, you just
    >> > have to suck it and see sometimes

    >
    >> >
    >> > > to try removing a disk and reading it non-raided in a different computer.
    >> >
    >> > > If that works, it should also work in the future ;-)
    >> >
    >> > Or not.
    >> > Babblebot's way of saying he didn't understand at all what previous
    >> > poster was saying
    >> >

    >
    >> I was gonna say, that's what I said,

    >
    >Why would the babblebot repeat what you said?
    >
    >> more or less.

    >
    >It's obviously gonna work in that particular computer that he would
    >have checked it in but that doesn't mean it will work in any new
    >computer he might buy when/if the actual incident is going to happen.


    Well, "that doesn't mean it will" is true, but irrelevant -
    the variable is not whether that worked, only whether the
    original system uses a standard config which can take a
    drive with data already on it and add that as a source
    member of a RAID1 array. If it can do that, there is no
    reason to believe it will make any changes to the drive that
    would prevent use in any other system that would've
    otherwise supported the same drive if it were a single
    logical volume, because essentially a RAID1 IS two single
    logical volumes, that's the whole point of it.


    >By the time it happens computers without RAID capability may not be
    >available anymore.


    Which is also a bit irrelevant, since the issue supposed was
    IF it'd need be a RAID controller and IF that were true the
    issue isn't just does it have RAID or not but rather is the
    RAID controller very nearly the same. Even a different bios
    for the same raid controller has the potential to break
    things, but fortunately since we're talking about RAID1
    these factors don't matter.


    >RAID controllers may well check in specific places
    >for any evidence of previous raid implementation and refuse to accept
    >it when its not their own, even if you want to use it as non-raided.


    False. If the RAID array depended on the metadata to
    identify the configuration and could not do so, it would not
    be able to create an array with two drives. Since a RAID1
    does not need to have an array with two drives in order to
    read the data off of either drive, which is again the whole
    point of RAID1, and since a drive that held data which had
    never been in any array can be made the source in a new
    array, we can conclude that even if there were a case where
    a new/different controller wouldn't make a RAID1 array with
    these two drives without having to wipe and recreate it on
    the 2nd drive - it still wouldn't matter since either is an
    independent volume holding all the data. The drive could
    simply be read as a single drive span.



    >To avoid such unwanted behaviour the RAID capability must be able
    >to be switched off entirely.


    There's no such distinction necessary. Hook either of the
    drives up to a raid or non-raid controller, period. No
    special thoughts or actions or features required.



    >
    >Like you said, it depends.


    Name 1 controller less than several years old that can't
    take a RAID1 member and read off the data, assuming
    otherwise compatible in a very basic way (same data
    interface, SATA or PATA, supporting the drive capacity if
    PATA, etc).

  12. Re: RAID1 - what happens if your motherboard RAID controller dies?

    On Fri, 23 May 2008 11:06:50 -0400, kony
    wrote:

    >On Thu, 22 May 2008 13:25:45 -0700 (PDT),
    >clangers_snout@yahoo.co.uk wrote:
    >
    >>I have a motherboard with a hardware RAID controller built in and I
    >>intend to set up two identical drives in RAID 1 configuration. My
    >>worry is how I would go about recovering the data from either drive if
    >>my motherboard goes down. I assume that you can't just plug one of the
    >>drives in to another motherboard and expect it to be read by a normal
    >>SATA2 (in my case) connection. So how would I recover the data in this
    >>worst case condition?

    >
    >Unlike other RAID levels, a RAID1 does not need metadata to
    >work and in fact can be made on any normal controller by
    >taking a drive that was not a member of any raid array,
    >hooking it up to the controller, then telling the controller
    >to dupe that onto a second drive.


    I should elaborate on what I wrote above. A RAID1 does need
    the metadata to exist and be understood by the controller
    (which must have the RAID1 funcitonality) in order to
    continue functioning as a two drive mirror of a single
    logical volume but that is not necessary to read the data
    off either member alone.

  13. Re: RAID1 - what happens if your motherboard RAID controller dies?

    In comp.sys.ibm.pc.hardware.storage kony wrote:
    > On Fri, 23 May 2008 11:06:50 -0400, kony
    > wrote:


    >>On Thu, 22 May 2008 13:25:45 -0700 (PDT),
    >>clangers_snout@yahoo.co.uk wrote:
    >>
    >>>I have a motherboard with a hardware RAID controller built in and I
    >>>intend to set up two identical drives in RAID 1 configuration. My
    >>>worry is how I would go about recovering the data from either drive if
    >>>my motherboard goes down. I assume that you can't just plug one of the
    >>>drives in to another motherboard and expect it to be read by a normal
    >>>SATA2 (in my case) connection. So how would I recover the data in this
    >>>worst case condition?

    >>
    >>Unlike other RAID levels, a RAID1 does not need metadata to
    >>work and in fact can be made on any normal controller by
    >>taking a drive that was not a member of any raid array,
    >>hooking it up to the controller, then telling the controller
    >>to dupe that onto a second drive.


    > I should elaborate on what I wrote above. A RAID1 does need
    > the metadata to exist and be understood by the controller
    > (which must have the RAID1 funcitonality) in order to
    > continue functioning as a two drive mirror of a single
    > logical volume but that is not necessary to read the data
    > off either member alone.


    True. There are RAID 1 controllers, however, that put the
    metadata at the beginning od the disk and translate everything
    after. I don't know how common that is today, but it used to be
    a problem. If you can take a disk out of a RAID1 and access
    it without any special measures (LVM translation, e.g.) on
    a non-RAID controller, then the metadata is very likely at
    the end or not on disk at all.

    Reasons for putting the metadata at the beginning are the
    usual: Lazyness, stupidity or a desire to bind you to
    a specific product.

    Arno

  14. Re: RAID1 - what happens if your motherboard RAID controller dies?

    Good discussion, learned a lot of it, since I've got the same thoughts
    like starter clangers_....
    Question: To me it seems like ICH9R from Intel is popular at the
    moment for constructing RAIDs. Might be true or not. But, given the
    ICH9R, where does it put these metadata? Does anybody know? Any
    experiences anybody about pulling off one RAID1-drive from an ICH9R to
    whatever SATA-connector? Does this single special thing out of the big
    variety of RAID-Levels and controllers work?

    Reagrds,
    Frank

  15. Re: RAID1 - what happens if your motherboard RAID controller dies?

    Frank wrote:
    > Good discussion, learned a lot of it, since I've got the same thoughts
    > like starter clangers_....
    > Question: To me it seems like ICH9R from Intel is popular at the
    > moment for constructing RAIDs. Might be true or not. But, given the
    > ICH9R, where does it put these metadata? Does anybody know? Any
    > experiences anybody about pulling off one RAID1-drive from an ICH9R to
    > whatever SATA-connector? Does this single special thing out of the big
    > variety of RAID-Levels and controllers work?
    >
    > Reagrds,
    > Frank


    I think the answer to this one is simple.

    You don't need to know where the metadata is stored :-)

    Why ? Because RAID1 is not a substitute for backups.

    Consider the following scenarios.

    1) You download a virus. It zeros a single sector in the middle
    of every MP3 file you have stored on the computer. Does the
    RAID1 mirror protect from this fault ? No. Both disks have
    the exact same (virus damaged) files stored on them.

    2) Consider the power supply fails in the computer. The 12V rail
    rises to 15V. The motors on both hard drives are burned instantly.
    Does the RAID1 help you now ? No. Both disks are dead. Same
    thing, if there was an electrical storm passing overhead, and
    your house AC is hit. Both motherboard and drives could be
    ruined.

    That is why you have daily backups - incremental and full backups.
    If the computer is destroyed, you reach for that USB external enclosure
    you use on a daily basis, and you do a cold metal restore to
    the newly constructed computer. Now it doesn't matter where the
    metadata is. Because the backup image has captured the data.
    By storing the USB external enclosure in a safe place, away
    from the computer, there are better odds it'll survive an
    act of God.

    Another point. If you're going RAID1, connecting the computer
    to an uninterruptible power supply. If the uninterruptible power
    supply has a serial cable to connect to the back of the computer,
    that will allow an automated and orderly shutdown if you aren't
    present when the power goes off. That will help maintain the exact
    mirroring of your RAID1 drives. Otherwise, an abrupt shutdown, could
    leave divergent contents.

    Paul

  16. Re: RAID1 - what happens if your motherboard RAID controller dies?

    In comp.sys.ibm.pc.hardware.storage Frank wrote:
    > Good discussion, learned a lot of it, since I've got the same thoughts
    > like starter clangers_....
    > Question: To me it seems like ICH9R from Intel is popular at the
    > moment for constructing RAIDs. Might be true or not. But, given the
    > ICH9R, where does it put these metadata? Does anybody know? Any
    > experiences anybody about pulling off one RAID1-drive from an ICH9R to
    > whatever SATA-connector? Does this single special thing out of the big
    > variety of RAID-Levels and controllers work?


    > Reagrds,
    > Frank


    I don't know what exactly Intel does, but it seems Linux dmraid
    (the fakeraid driver) can access intel RAID arrays. That means
    even without the controller the disks are accessible with Linux.

    It seems Intel stores the metadata in the last two sectors of the
    disk (but I found no hard evidence, just heresay). If true,
    that would mean that you can use the individual disks in a RAID1 on
    any non-raid controller.

    Arno

  17. Re: RAID1 - what happens if your motherboard RAID controller dies?

    On Mon, 26 May 2008 11:01:04 -0700 (PDT), Frank
    wrote:

    >Good discussion, learned a lot of it, since I've got the same thoughts
    >like starter clangers_....
    >Question: To me it seems like ICH9R from Intel is popular at the
    >moment for constructing RAIDs. Might be true or not. But, given the
    >ICH9R, where does it put these metadata? Does anybody know? Any
    >experiences anybody about pulling off one RAID1-drive from an ICH9R to
    >whatever SATA-connector? Does this single special thing out of the big
    >variety of RAID-Levels and controllers work?
    >
    >Reagrds,
    >Frank


    Some who have mentioned metadata at the start of a drive are
    muddying the waters, like saying it's possible there are
    pink elephants even though they are rare. Odd things
    happened years ago but today there's one thing to say about
    metadata on the start of a drive - don't use a controller
    that does this if you can ever find one.

    Practically every modern raid controller puts the metadata
    on the rear end of the drive. You can test this easily
    enough, if you can take a drive with data on it, define it
    as a source or primary in the raid configurator for a raid1.
    and still retain all data. There is however a chance
    someone could make the wrong choice in the configurator
    (raid bios or raid manager software) and it would wipe out
    the partition table, sector 0 - and of course the data from
    a logical perspective of being unable to access it as-is,
    even though the bits are still on the platters it is
    prepared for a new partition and filesystem to be created,
    not wiped out because the metadata was placed there.



  18. Re: RAID1 - what happens if your motherboard RAID controller dies?

    In comp.sys.ibm.pc.hardware.storage kony wrote:
    > On Mon, 26 May 2008 11:01:04 -0700 (PDT), Frank
    > wrote:


    >>Good discussion, learned a lot of it, since I've got the same thoughts
    >>like starter clangers_....
    >>Question: To me it seems like ICH9R from Intel is popular at the
    >>moment for constructing RAIDs. Might be true or not. But, given the
    >>ICH9R, where does it put these metadata? Does anybody know? Any
    >>experiences anybody about pulling off one RAID1-drive from an ICH9R to
    >>whatever SATA-connector? Does this single special thing out of the big
    >>variety of RAID-Levels and controllers work?
    >>
    >>Reagrds,
    >>Frank


    > Some who have mentioned metadata at the start of a drive are
    > muddying the waters, like saying it's possible there are
    > pink elephants even though they are rare. Odd things
    > happened years ago but today there's one thing to say about
    > metadata on the start of a drive - don't use a controller
    > that does this if you can ever find one.


    > Practically every modern raid controller puts the metadata
    > on the rear end of the drive.


    Good to know that this design mistake is now typically
    fixed. People may still have older hardware or get older
    hardware from eBay, for example. In that case they need
    to be aware of the potential problem.

    > You can test this easily
    > enough, if you can take a drive with data on it, define it
    > as a source or primary in the raid configurator for a raid1.
    > and still retain all data.


    Huh? This does not seem to make any sense.

    Here is what you can do (linux):
    1) Attach dribe to a non-RAID interface or configure it
    as pass-trough/raw. Blank the start of a drive with zeros
    head -c 10240 /dev/zero
    Overwrites the firsth 20 secotrs with zeros. Should
    be enough
    2) Create a RAID on this disk with your controller.
    3) Re-attach it in the form in 1) and look at the
    first 20 sectors, e.g. by doing
    head -c 10240 | hex

    I anything was changed, be wary. This controller may put
    the metadata at the satrt or mess with the MBR. Both not
    good.

    Arno

  19. Re: RAID1 - what happens if your motherboard RAID controller dies?

    kony wrote in news:date34thjj4ev454t5fs2809c4tgjuslov@4ax.com
    > On Sat, 24 May 2008 00:09:54 +0100, "Squeeze" wrote:
    > > SteveH wrote in news:LKuZj.8101$DZ6.6937@text.news.virginmedia.com
    > > > Squeeze wrote:

    > >
    > > Some context restored:
    > > > > This does not mean however that it will work this way every time, you just
    > > > > have to suck it and see sometimes

    > >
    > > > >
    > > > > > to try removing a disk and reading it non-raided in a different computer.
    > > > >
    > > > > > If that works, it should also work in the future ;-)
    > > > >
    > > > > Or not.
    > > > > Babblebot's way of saying he didn't understand at all what previous
    > > > > poster was saying
    > > > >

    > >
    > > > I was gonna say, that's what I said,

    > >
    > > Why would the babblebot repeat what you said?
    > >
    > > > more or less.

    > >
    > > It's obviously gonna work in that particular computer that he would
    > > have checked it in but that doesn't mean it will work in any new
    > > computer he might buy when/if the actual incident is going to happen.


    > Well, "that doesn't mean it will" is true, but irrelevant -


    If the drive is rejected then that's very relevant.

    > the variable is not whether that worked, only whether the original
    > system uses a standard config which can take a drive with data
    > already on it and add that as a source member of a RAID1 array.


    > *If* it can do that, [then] there is no reason to believe it will make any
    > changes to the drive


    Why not. There must still be information stored /somewhere/ that sig-
    nals whether the drives are in sync or that the mirror needs to be rebuilt.
    Such information won't be on a standard non-raided drive.

    > that would prevent use in any other system


    Well, that's up to the people who designed/wrote the particular RAID
    bios of that other system. I can't speak for them and neither can you.

    [snip]

  20. Re: RAID1 - what happens if your motherboard RAID controller dies?

    Arno Wagner wrote in news:69pp1mF33lfgkU2@mid.individual.net
    > In comp.sys.ibm.pc.hardware.storage kony wrote:
    > > On Fri, 23 May 2008 11:06:50 -0400, kony wrote:
    > > > On Thu, 22 May 2008 13:25:45 -0700 (PDT), clangers_snout@yahoo.co.uk wrote:
    > > >
    > > > > I have a motherboard with a hardware RAID controller built in and I
    > > > > intend to set up two identical drives in RAID 1 configuration. My
    > > > > worry is how I would go about recovering the data from either drive if
    > > > > my motherboard goes down. I assume that you can't just plug one of the
    > > > > drives in to another motherboard and expect it to be read by a normal
    > > > > SATA2 (in my case) connection. So how would I recover the data in this
    > > > > worst case condition?
    > > >
    > > > Unlike other RAID levels, a RAID1 does not need metadata to work and
    > > > in fact can be made on any normal controller by taking a drive that was
    > > > not a member of any raid array, hooking it up to the controller, then tel-
    > > > ling the controller to dupe that onto a second drive.

    >
    > > I should elaborate on what I wrote above. A RAID1 does need
    > > the metadata to exist and be understood by the controller (which
    > > must have the RAID1 funcitonality) in order to continue functioning
    > > as a two drive mirror of a single logical volume but that is not
    > > necessary to read the data off either member alone.

    >
    > True. There are RAID 1 controllers, however, that put the metadata
    > at the beginning od the disk and translate everything after. I don't
    > know how common that is today, but it used to be a problem. If you
    > can take a disk out of a RAID1 and access it without any special
    > measures (LVM translation, e.g.) on a non-RAID controller,


    > then the metadata is very likely at the end


    Or at the 'beginning'.
    "Beginning" is a relatively imprecise description, Babblebot.
    Where does it say that "beginning" has to be sector 0, eh?

    > or not on disk at all.


    There should at least be some extra information to control the validity
    and status of the configuration.

    >
    > Reasons for putting the metadata at the beginning are the usual:
    > Lazyness, stupidity or a desire to bind you to a specific product.


    Or just because there is enough unused space near the start of the drive
    that can be used for it's own purposes without interfering with standard
    partitioning and/or formatting, Babblebot.

    >
    > Arno


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