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RAID with 3 Disks ?
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RAID with 3 Disks ?

HindiHindi Member
edited August 2019 in Help

Hii LET,

Im ordering a server that gives me 3 X 1 TB HDDs.

I was looking for RAID 1.
Now, we know that RAID 1 needs two drives.

So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

Will it be still available for use ?

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Comments

  • FalzoFalzo Member
    edited August 2019

    @Hindi said:
    Hii LET,

    Im ordering a server that gives me 3 X 1 TB HDDs.

    I was looking for RAID 1.
    Now, we know that RAID 1 needs two drives.

    So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

    Will it be still available for use ?

    you can do raid-1 with three disks as well, it just adds another mirror-drive. most likely it simply depends on the installer you use or where you do that 'selecting' ;-)

    Thanked by 1Hindi
  • donlidonli Member
    edited August 2019

    You specifically tell it which disk devices you want to put in the Raid 1. Just don't include the 3rd disk (or you can include it as a spare device as part of the raid).

    When asking questions like this, please specify the operating system you will be using.

    Thanked by 1Hindi
  • LeviLevi Member

    My suggestion is to just use zfs. It's like raid on steroids ;)

    Thanked by 1Hindi
  • HindiHindi Member
    edited August 2019

    Thank you all for your guidance.

    @donli said:
    You specifically tell it which disk devices you want to put in the Raid 1. Just don't include the 3rd disk (or you can include it as a spare device as part of the raid).

    When asking questions like this, please specify the operating system you will be using.

    CentOS 7 for cPanel Server.
    I have these options with my provider :smile:

    Please suggest which one should i go with. my requirement is to use only 2 x 1 TB. I will do what you suggest with the third one, may be for a backup ?

    EDIT : there is an option for "Advanced cPanel Partitioning" as well. IPMI access is there.

  • JunJun Member

    Can't tell what those options mean. The same word, raid1, can mean a lot of different options. For example, btrfs raid1 can use all three disks to give you 1.5TB of storage. If it is mdadm, you can use all three disks for 3-way RAID 1 which is tolerant to two disks failures, or you can set up two-way RAID 1 with 1 spare disk. In the end, the technician who will set up the disk for you is the only one who knows the details. Just file a ticket to the provider.

  • ViridWebViridWeb Member, Host Rep

    @Hindi said:
    Hii LET,

    Im ordering a server that gives me 3 X 1 TB HDDs.

    I was looking for RAID 1.
    Now, we know that RAID 1 needs two drives.

    So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

    Will it be still available for use ?

    RAID 5 is more suitable for 3 drive in my opinion. It can tolerate 1 Dive failure and you will get 2TB storage

    Ypu can also do the RAID 1 and will survive up to 2 drive failure but then you will have to work with only 1TB storage..

    Check here and calculate the most suitable RAID for you
    http://www.raid-calculator.com/

  • NeoonNeoon Community Contributor, Veteran

    Raid is overrated, if you want to cripple it go with Raid 5.
    I would suggest Raid 1.

    Thanked by 1ViridWeb
  • Tr33nTr33n Member
    edited August 2019

    I would either use a RAID-Z1 or RAID 1. As ZFS is not available, better be on the safe side and go with a RAID 1.

    ViridWeb said: RAID 5 is more suitable for 3 drive in my opinion. It can tolerate 1 Dive failure and you will get 2TB storage

    A mdadm RAID 5 has a good chance to fail during rebuild due to the possible URE issue. Especially at larger disks.
    Calculate your chance of complete data loss here.

    Thanked by 1ViridWeb
  • ViridWebViridWeb Member, Host Rep

    @Tr33n said:
    I would either use a RAID-Z1 or RAID 1. As ZFS is not available, better be on the safe side and go with a RAID 1.

    ViridWeb said: RAID 5 is more suitable for 3 drive in my opinion. It can tolerate 1 Dive failure and you will get 2TB storage

    A mdadm RAID 5 has a good chance to fail during rebuild due to the possible URE issue. Especially at larger disks.
    Calculate your chance of complete data loss here.

    Yes you are absolutely right..
    But in this case OP didn't mention what work he wants to do or how much storage he needs..

    So I suggest both of them including RAID 1 in details about how much storage he will get and etc.

    Now it's his decision..

    But it's always better to gp with security and not storage.

    In that case RAID 1 strongly recommend..

  • If you want parity but still a lot of storage, a 3-drive raid5 is possible, if you have 3x3tb (9tb total) of disks, 6tb will be available for ex.

  • @Hindi said:
    Thank you all for your guidance.

    @donli said:
    You specifically tell it which disk devices you want to put in the Raid 1. Just don't include the 3rd disk (or you can include it as a spare device as part of the raid).

    When asking questions like this, please specify the operating system you will be using.

    CentOS 7 for cPanel Server.
    I have these options with my provider :smile:

    Please suggest which one should i go with. my requirement is to use only 2 x 1 TB. I will do what you suggest with the third one, may be for a backup ?

    EDIT : there is an option for "Advanced cPanel Partitioning" as well. IPMI access is there.

    simply depends on your capabalities in administering a server ;-)

    either check what the advanced partitioning has to offer, maybe it shows enougb options.
    or just use the raid-1 option and if it uses all three disks remove one disk from the array (probably md-raid) later for whatever purpose.
    or install completely manually via IPMI and built the raid yourself to your needs.

  • jsgjsg Member, Resident Benchmarker

    @Hindi said:
    Hii LET,

    Im ordering a server that gives me 3 X 1 TB HDDs.

    I was looking for RAID 1.
    Now, we know that RAID 1 needs two drives.

    So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

    Will it be still available for use ?

    Yes, it will. You can have Raid 1 over 2 drives plus still use the third drive "naked".

    But to offer good and useful advice we would need to have some more info. Probebly the most important is -> What are your priorities? The speed of the solution? The reliability and safety? The available net disk space? It might also be helpful to tell us what that server will be mainly used for.

  • RAID 0 FTW. Triple the speed, triple the space.

    Thanked by 1uptime
  • ViridWebViridWeb Member, Host Rep

    @yokowasis said:
    RAID 0 FTW. Triple the speed, triple the space.

    Why are you suggesting a dumb config?
    If a single disk fail, all data will be destroy with that RAID 0

    If you have no knowledge about tech then please stay away from other's thread

  • ViridWebViridWeb Member, Host Rep

    @Hindi said:
    Hii LET,

    Im ordering a server that gives me 3 X 1 TB HDDs.

    I was looking for RAID 1.
    Now, we know that RAID 1 needs two drives.

    So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

    Will it be still available for use ?

    A small recommendation, Just try to get a 4 x 1 TB server
    with this you can use RAID10
    Also 4x read and 2x write speed gain

  • @ViridWeb said:

    @yokowasis said:
    RAID 0 FTW. Triple the speed, triple the space.

    Why are you suggesting a dumb config?
    If a single disk fail, all data will be destroy with that RAID 0

    If you have no knowledge about tech then please stay away from other's thread

    Hows that a dumb config? Granted its terrible for data redundancy but if he has good offsite backups somewhere and data isn't critical then maybe the speed would be better. Depends entirely on his usecase

  • yokowasisyokowasis Member
    edited August 2019

    @ViridWeb said:

    @yokowasis said:
    RAID 0 FTW. Triple the speed, triple the space.

    Why are you suggesting a dumb config?

    You are clearly new to LET.

    Edit :
    Looked at your profile. Yup. Nailed it.

    Thanked by 2beagle ulayer
  • @ViridWeb said:

    @Hindi said:
    Hii LET,

    Im ordering a server that gives me 3 X 1 TB HDDs.

    I was looking for RAID 1.
    Now, we know that RAID 1 needs two drives.

    So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

    Will it be still available for use ?

    A small recommendation, Just try to get a 4 x 1 TB server
    with this you can use RAID10
    Also 4x read and 2x write speed gain

  • ViridWebViridWeb Member, Host Rep

    @cybertech said:

    @ViridWeb said:

    @Hindi said:
    Hii LET,

    Im ordering a server that gives me 3 X 1 TB HDDs.

    I was looking for RAID 1.
    Now, we know that RAID 1 needs two drives.

    So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

    Will it be still available for use ?

    A small recommendation, Just try to get a 4 x 1 TB server
    with this you can use RAID10
    Also 4x read and 2x write speed gain

    Hahaha.. But to fire a bullet we need a gun..

  • RAID 1 is possible with 3 HDD's. I'm doing the same with my servers 3x3TB with RAID 1

  • @ViridWeb said:

    @cybertech said:

    @ViridWeb said:

    @Hindi said:
    Hii LET,

    Im ordering a server that gives me 3 X 1 TB HDDs.

    I was looking for RAID 1.
    Now, we know that RAID 1 needs two drives.

    So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

    Will it be still available for use ?

    A small recommendation, Just try to get a 4 x 1 TB server
    with this you can use RAID10
    Also 4x read and 2x write speed gain

    Hahaha.. But to fire a bullet we need a gun..

    You obviously do not know bullets very well either. Never needed a gun to fire a bullet in the history of bullets. A nail and pipe will work as well. Chuck a bullet into a fire and see what happens to it. (if you do the last one you better run like your ass is on fire)

  • ViridWebViridWeb Member, Host Rep

    @AuroraZ said:

    @ViridWeb said:

    @cybertech said:

    @ViridWeb said:

    @Hindi said:
    Hii LET,

    Im ordering a server that gives me 3 X 1 TB HDDs.

    I was looking for RAID 1.
    Now, we know that RAID 1 needs two drives.

    So, If i select RAID 1 ( software RAID ) , what happens to the 3rd drive ?

    Will it be still available for use ?

    A small recommendation, Just try to get a 4 x 1 TB server
    with this you can use RAID10
    Also 4x read and 2x write speed gain

    Hahaha.. But to fire a bullet we need a gun..

    You obviously do not know bullets very well either. Never needed a gun to fire a bullet in the history of bullets. A nail and pipe will work as well. Chuck a bullet into a fire and see what happens to it. (if you do the last one you better run like your ass is on fire)

    Ya I know they will behave like popcorn and will make an extra hole in my body..:P

  • Thank you guys... I went ahead with 2 x 4 TB , RAID 1

  • Guess I'm too late... but just FYI some controllers do support RAID 1E that takes 3 drives, and I believe mdadm supports it as well.

    I used this years ago (due to slot limitations) and the array is working just fine for years, not a common thing one would normally do though.

  • You can also do raid1 with one hot spare.

  • SpryServers_TabSpryServers_Tab Member, Host Rep

    @marvel said:
    You can also do raid1 with one hot spare.

    I was just about to suggest this. I can't believe no one else has. It's really the most logical thing to do.

    Thanked by 2XiNiX uptime
  • SpryServers_Tab said: I can't believe no one else has.

    The second reply did mention spare, without hot though. :)

  • Jun said: For example, btrfs raid1 can use all three disks to give you 1.5TB of storage.

    This is what I'd do! Also enable the transparent filesystem compression option if you have CPU cycles to burn. Also run weekly scrubs via cron!

  • reliablevps_usreliablevps_us Member, Patron Provider

    I would always check my raid configuration with this tool before deployment.
    http://ibeast.com/tools/RaidCalc/RaidCalc.asp

    Answer to your question setting up RAID 1 on three disks just does not make since , since RAID 1 is basically mirror of your data on 2 disks if one fails the second one will cover.
    Performance wise you get double the read speeds and you are capped on write speeds to one disk.

    If you are looking for decent multiprocessing read speeds and still have redundancy i would go with RAID 5.

  • raindog308raindog308 Administrator, Veteran

    yokowasis said: RAID 0 FTW. Triple the speed, triple the space.

    YOLORAID!

    Tr33n said: A mdadm RAID 5 has a good chance to fail during rebuild due to the possible URE issue. Especially at larger disks. Calculate your chance of complete data loss here.

    I've grown to hate RAID5. My home file server has 6x6TB disks, and I do them as three 2-disk pairs. Costs more disk, but I got tired of RAID failures. I've also noticed that I have far fewer RAID problems period with RAID1.

    If we're talking some big enterprise storage array where they've got PhDs engineering everything using top-notch disks, sure, whatever they recommend...but I've had tons more problems with RAID5 on mdadm than I ever had with RAID1.

    Thanked by 1uptime
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