RAID5 with unexplained error

  • Hi,


    beginning from the start-post if have a question:


    How did you use your box? 24/7? Powering down the box anyway?


    The errors are not raid related - only FS related. And this seems that you (sometimes?) hard cut the power off your system, or something similar.


    Hint:
    fsck needs often more runs ...


    And what is the recommendation for the 3X3TB drives I have? I need at least 6 GB for storage.


    - Backup, Backup and Backup ... then the redundancy is optional :P
    - RAID5 (even it is "only 4 business contiuity" ... it makes this job)
    - ZFS-Z1 (more complex than RAID, but also more powerful - very RAM aggressive)
    - SnapRAID
    - single disks (or LVM) with rsync-construct
    - UPS (USV in german)


    Sc0rp

    • Offizieller Beitrag

    So what is the recommendation for recreating my system?


    I have an 240GB SSD for the OMV system, what FS it should be?


    And what is the recommendation for the 3X3TB drives I have? I need at least 6 GB for storage.

    Realize that there are many ways to set up OMV, and much of it comes down to preference.


    I use 32GB USB 3.0 thumb drives (a good brand - Sandisk) for a few reasons.
    - With a 24x7 server, the speed of booting up doesn't really matter. How often will you reboot? Once a month?
    In my opinion, after the boot is complete a speedy boot drive doesn't give you much, if anything, in the way of performance. So, I've found that a USB 3.0 thumb drive is plenty fast enough.
    - USB drives are easy to clone. With a clone, ready to go, you can back out of an update that has gone south and easily recover if system files get corrupted. I maintain 3 drives. A master that only gets updated with version upgrades and reconfigurations, then it goes in a drawer. I have 2 more that get the day to day wear with the usual package updates and minor config changes.
    - Thumb drives use external plugs. I have one plugged in and active, and another sitting on top of the case. If the boot drive dies I can recover in, literally, a minute or two.
    (If you decided to boot on USB thumb drives, you'd need to add the flash memory plugin.)


    I use ext4 to boot because, since I have plenty of backup, a simple file system gets it done.


    For data I have a ZFS mirror that I backup to different devices on varying time intervals. (Backup doesn't have to be expensive. It can be an old PC with a single drive large enough to copy the data contents of your data drive/array.) Currently, I use rsync and replicate changes to data files, but I'm looking into rotating ZFS snap shots.


    With 3TB drives (3 each) and a 6TB requirement, if using ZFS, you'd have to go with raidZ1. Doing something else would require another 3TB drive.

  • - USB drives are easy to clone. With a clone, ready to go, you can back out of an update that has gone south and easily recover if system files get corrupted. I maintain 3 drives. A master that only gets updated with version upgrades and reconfigurations, then it goes in a drawer. I have 2 more that get the day to day wear with the usual package updates and minor config changes

    @flmaxey Which tool do you use to clone the thumb drives? clonezilla disk to disk or something else?

    OMV 3.0.100 (Gray style)

    ASRock Rack C2550D4I C0-stepping - 16GB ECC - 6x WD RED 3TB (ZFS 2x3 Striped RaidZ1) - Fractal Design Node 304 -

    3x WD80EMAZ Snapraid / MergerFS-pool via eSATA - 4-Bay ICYCube MB561U3S-4S with fan-mod

    Einmal editiert, zuletzt von cabrio_leo ()

  • I did experience some power failures recently which I assume might caused this FS issue.


    Will RAIDZ1 can also cope with such issue?

    • Offizieller Beitrag

    I've used clonezilla but the easiest utility to use, without having to reboot a client, is Wind32Diskimager. It will "read" the contents of a USB drive, SDcard, etc., to a *.img file. (The file also becomes another form of extra backup, so I add the date to the file name.) I write USB thumb drives using Win32Diskimager as well.
    ____________________________________________


    Given TK's notes on Etcher and write verification, for writing SDcards, the safest route is to:


    -Delete all contents or reformat the SDcard.
    -Test the SDcard with h2testw.exe
    (And, if there are no errors)
    -Write the *.img file to the card using Etcher.


    From experience in dealing with SDcards, I've found it's best to error on the safe side.

  • Re,

    Will RAIDZ1 can also cope with such issue?

    More or less, "cutting" the power off destroys any information held in caches ... hdd-cache & RAM, which affects any FS.
    ZFS brings the best algorithms to deal with that, but unexpected powerloss should be avoided at all!


    Sc0rp

    • Offizieller Beitrag

    Re,

    More or less, "cutting" the power off destroys any information held in caches ... hdd-cache & RAM, which affects any FS.ZFS brings the best algorithms to deal with that, but unexpected powerloss should be avoided at all!


    Sc0rp

    I agree with Sc0rp.


    Hard shut downs can have serious unintended consequences regardless of the file system used. Ext4, with its journaling feature, is supposed to be able to deal with it but, as many on this forum would tell you, it's not perfect.
    (Which is why I like having 3 verified working copies of my boot drive. ;) There's no point in trying to sort out bizarre file system issues. Plug in a backup and go.)


    Where the file system on your storage array is concerned, a modern file system like ZFS is purposed designed and built to deal with dirty shutdown issues and a host of other error producing events. It's a CoW file system that "Copies on Write" which means it write commits a change to a file, check sums and verifies it (important), before abandoning the original. Even with these excellent features, an UPS with surge suppression is a very good idea.


    If you go with ZFS, after the array is created, but before setting shared folders, etc. Go on the command line and apply the following. It's easier than editing the pool in the GUI. ("yourpoolname" is whatever you named your pool):



    Code
    zfs set aclinherit=passthrough yourpoolname
    zfs set acltype=posixacl yourpoolname
    zfs set xattr=sa yourpoolname
    zfs set compression=lz4 yourpoolname


    Out of the box, ZFS supports Solaris permissions. You want "Linux" permissions. That's what the above does.
    (And from what I've gathered here and elsewhere; lz4 compression won't hurt anything and, with uncompressed files, it might actually save some array space.)

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