Raspberry Pi4 4gb Raid 5 questions

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    • Raspberry Pi4 4gb Raid 5 questions

      Ok so just recently joined and looking for some help and will appreciate any advice. I recently bought a Raspberry Pi4 4gb and want to set it up with Open Media Vault and want redundancy. I want to hook up a 5 bay DAS to it and was wondering should I go for a DAS with Raid 5 integrated into it or should I go with a cheaper option without Raid 5 integrated and use software based Raid 5 in OMV? I also possibly somewhere down the line would like to attach another DAS in a Raid 1 configuration to use as backup for more important things that I could keep locally instead of relying on cloud based services. The Raid 5 drives would be 3 x 3TB and 2 x 4TB. The Raid 1 drives would be 2 x 2TB but would be older then the other drives but not bought/used the same amount so hopefully both wouldn't fail at the same time. Thanks for any info :)
    • First things first: Raid is no backup. So, do you really need the high availibility of a RAID?

      I´d never do a Raid setup again. I´ve had so many problems (degraded Raids, missing volumes etc...) Just search the Forum.

      I know, many people say "cloud is bad". But honestly, for a safe and cheap backup - nothing is better. If you choose the right service, backing up data is their key competence.

      I say "cheap" because I´ve been thinking about the last years what is important and what is not. So I think about every file what goes on any of my NAS drives --> "is it really important?" And then I decide where to store: My setup at the moment are just some big drives for data and some smaller drives for important stuff. Data is not backed up in any way. I can live with that. Important stuff is backed up to a big external HDD (for fast access if main hdds fail) and for a worst case scenario also into the cloud.


      To answer at least a few of your questions:
      If you want to use just a RasPi to do everything, I suggest the DAS to do the Raid.
      OMV 4.x| HP Microserver | 256GB Samsung 830 SSD for system | 4x 2TB in a RAID5
      OMV 4.x| Odroid XU4 | 5TB Data drive | 500GB Backup drive
      OMV 5.x| Raspberry Pi 4 | 6TB Data drive | 500GB SSD drive
    • Scorpion3d wrote:

      The Raid 5 drives would be 3 x 3TB and 2 x 4TB.
      By that comment alone I would surmise you probably have not used a Raid set up before :)

      The external unit you referenced are designed for Windows whilst they have a dip switch on the rear they are reliant on the OS to initiate the dip switch setting, Linux cannot do this it will simply see them as individual drives.

      A Raid setup using USB drives has been disabled in OMV, if you want to use a Raid option it can be achieved by the command line, there are plenty of 'youtube gurus' who do this, but as far OMV is concerned, don't call us we'll call you :D
      Raid is not a backup! Would you go skydiving without a parachute?
    • Reconsider why you think that you need RAID. I suspect that you don't need RAID.

      If you get a RAID5 DAS, I think that you should have identical drives. Otherwise you may waste the extra storage on any drive bigger than the smallest drive.

      Also, if the DAS itself fails, all your data will be lost. Poof! You need to have at least one spare DAS enclosure or you will have a single point of failure, without any redundancy at all.

      I use a dual drive external enclosure with one of my RPi4. I use both drives for backups of other NAS. No RAID. But I could use the first drive for shared files and the second drive for rsync snapshot backups of the first. That would be a simple, efficient and very robust setup. If you use bigger drives you also lower power usage and lower the number of things that can fail. And you need fewer enclosures, USB cables and less space.
      OMV 4: 9 x Odroid HC2 + 1 x Odroid HC1 + 1 x Raspberry Pi 4
    • There is nothing redundant about an RPi. So, have redundant array of disks is not going to add much redundancy.
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    • Ok so the reason I want Raid 5 is I want some sense of recovery so if a hard drive decided to stop working I dont loose almost 3TB of data which I will somehow have to manage to get back. But at the same time I dont want to loose half of my storage to 1 to 1 backups. So from what I've read about Raid 5 in will loose 1 drive to parity data. And yes the whole 3 smaller and 2 larger drives I know with a Raid setup they will only use the smallest drives as a base. The 2 extra 4TB drives are extra ones I have and I'd rather loose out on 2TB of data then having to go out and buy 3 x 4TB drives.

      TerraMaster D5-300 USB3.0(5Gbps) Type C 5-Bay External Hard Drive RAID Enclosure Support RAID 5 Hard Drive RAID Storage (Up to 70TB, Diskless) smile.amazon.com/dp/B01KO03BBA…_r_cp_apa_i_UIDZDbEH43WWN

      That is the 5 bay DAS I am looking at.
    • Even with RAID you still need full backups if you don't want to loose data. I would suggest that backups are much more important than RAID.

      RAID ensures that program errors or user errors wipes data on all drives. Instantaneously. Redundancy gives no protection. No chance to recover. The only way to protect against that is snapshots and/or backups.

      If you don't care about loosing your data you don't need RAID either.
      OMV 4: 9 x Odroid HC2 + 1 x Odroid HC1 + 1 x Raspberry Pi 4
    • Scorpion3d wrote:

      So from what I've read about Raid 5 in will loose 1 drive to parity data.
      You obviously haven't been reading the right information, Raid wiki and here's the Raid Setup wiki and youtube for help with your project. I notice from your link to Amazon (which doesn't work) are you in the US? If so do you intend to use a UPS? Power outages are a common cause of data loss.

      Scorpion3d wrote:

      Ok so the reason I want Raid 5 is I want some sense of recovery
      There is no 'sense of recovery' in a Raid 5 only one drive can fail so you have a failed drive, you get a new one, set it up add it to the array, whilst the Raid is rebuilding it stops, why because another drive has failed. What to do, nothing, because the Raid is now dead all data has been lost, BTDTGTTS.

      I can't find a thread a new user had responded too in respect of a Raid on a Pi, he had used a bitcoin mining case, 4/5 2.5" drives, Pi4 and a USB3 recharging hub, neat setup, but he was using MergerFS and SnapRaid.
      Raid is not a backup! Would you go skydiving without a parachute?
    • Scorpion3d wrote:

      Based in Ireland so thankfully power cuts aren't an issue.
      :) well I'm in the UK and I don't have one :thumbup:

      Scorpion3d wrote:

      Could I use it with this have a few HDD's
      For that price you could get a quality second hand commercial server from ebay far more reliable than a Pi with an externally attached storage. But if I was to use something like that attached to a Pi it would for backup purposes only.

      You could use MergerFS and SnapRaid, there is only one caveat I have found with that, if you use docker, which you would do to set up a media server, container configs are better located on a separate hard drive or SSD, which is how I have mine set up.
      Raid is not a backup! Would you go skydiving without a parachute?
    • geaves wrote:

      Scorpion3d wrote:

      Ok so the reason I want Raid 5 is I want some sense of recovery
      There is no 'sense of recovery' in a Raid 5 only one drive can fail so you have a failed drive, you get a new one, set it up add it to the array, whilst the Raid is rebuilding it stops, why because another drive has failed. What to do, nothing, because the Raid is now dead all data has been lost, BTDTGTTS.
      I can't find a thread a new user had responded too in respect of a Raid on a Pi, he had used a bitcoin mining case, 4/5 2.5" drives, Pi4 and a USB3 recharging hub, neat setup, but he was using MergerFS and SnapRaid.
      Raid is for Redundancy.
      And what you should do when a drive fail, is not to start rebuilding that array, instead you should immediately check that your backup is synchronized with the array and offload any important data that you can't afford to loose.
      Only when your data is secured can eventual rebuild of the array start.
      For a home user this should be the most important feature of a Raid array - the redudancy gives one second chance to backup important data. Without redundancy will data (most likely) be lost when a drive dies.

      After reading countless threads about Raid, this seems to be the number one mistake people do when a raid array gets degraded, they immediately start to rebuild the array.

      I can't comprehend this blasphemy about RAID5. As with all filesystems there are cons and pros. Raid5 is definitely not the worst out there.
      I chose RAID5 for my 4-disk home server 6 years ago because it is a good tradeoff between speed, redundancy and storage space.
      There has been two disk failures, one disk started to give bad blocks, one just died completely without warning. Both times was I able to recover important data to a backup, and could then replace the disk and rebuild array. It is still running!
    • Glider_bum wrote:

      It is still running!
      The purpose of your rant is what? Did you actually read the thread, obviously if a Raid option fits your purpose that's fine and the fact that you backup better still.
      The thread was about using a Raid option on a Raspberry Pi, you would recommend that would you well, here's someone else's thoughts about Raid for home use.
      Raid is not a backup! Would you go skydiving without a parachute?
    • geaves wrote:

      Glider_bum wrote:

      It is still running!
      The purpose of your rant is what? Did you actually read the thread, obviously if a Raid option fits your purpose that's fine and the fact that you backup better still.The thread was about using a Raid option on a Raspberry Pi, you would recommend that would you well, here's someone else's thoughts about Raid for home use.
      Soo... can't take a second opinion, can he not? :D
    • Glider_bum wrote:

      For a home user this should be the most important feature of a Raid array - the redudancy gives one second chance to backup important data. Without redundancy will data (most likely) be lost when a drive dies.
      The thing is, if you have really good backups, perhaps automated versioned snapshots, then there is no need for any redundancy.

      I suspect (and reading on this forum has confirmed it more than once) that RAID users often neglect or even ignore backups. Possibly because they hope that once a drive crash they have time to backup their data then. I think that is a very Bad™ way to protect your data.

      RAID provides no protection at all against user or program error. And I suspect that is a much more common way to lose data than by a drive crashing. I have never lost data to a crashed drive. But many times to my own mistakes and stupidity. If you by mistake delete a file or a folder, it is gone! Poff! RAID doesn't help then! Only backups and snapshots can protect against that. Then it is easy to restore that file or that folder.
      OMV 4: 9 x Odroid HC2 + 1 x Odroid HC1 + 1 x Raspberry Pi 4
    • Glider_bum wrote:

      I can't comprehend this blasphemy about RAID5
      I think raid5 can be a good thing when used on the right hardware. If you use cheap power supplies with old hard drives on a system that you put to sleep all the time (large percentage of OMV users), it doesn't make any sense. It makes even less sense when using arm boards with the drives connected to USB converters (another large percentage of OMV users). So, this is where the attitude comes from. If you are an experienced Linux user with good hardware then you aren't asking about raid and it doesn't apply to you.
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    • When I read the topic with "RPi" and "Raid" it was clear I would need popcorn...
      Many people setting up raid do not know how to handle them in case of a problem (at least I didn't know that when I first used a raid). Therefore, the support forums are full of people crying for help because their data is lost. So again, most people talking about raid have heard somewhere, that it is cool/save/fast/etc.. but don't know it. I wanted to have a raid because of speed. However, nowadays it is bullshit, if you want speed, just use a big SSD, which can easily saturate Gbit ethernet and soon 10G ethernet.
      If you want to sleep better thinking at your NAS, do not forget about Self-Monitoring, Analysis and Reporting Technology (SMART).

      Thankfully, SMART capabilities have become so powerful that all my drives which have failed in the last years (decades) did not fail silently, but were getting more and more errors over time. You could literally watch them aging before dying. At least, it was enough time to update the backup and plan the swap the drive without any downtime. That only works, if there is no single event which kills your hard drive (like power outage, fire, water leak, theft ...). However, in such an event, chances are high that all drives in that device fail at once which would also kill every raid.

      Invest the money you would spent on a hardware raid into a "real" PC. USB-powered hard drives might not be the best solution. It can work, but the risk is high, that there will be voltage drops or spikes from the USB controller, which the drive does not like. You do not want your controller to be the cheapest part of your setup (if the data is important)

      So:
      1) Automatic backup solution (no one manages to make manual backups as regularly as needed)
      2) Regular backups (depends on your data, hourly/daily)
      2) Use good Hardware to prevent failures (UPS, proper power supply (also USB drives don't like fluctuating power), ensure temperature being in recommended range..)
      3) Monitor your system/hardware (SMART) to detect aging before the drive fails
    • Adoby wrote:

      The thing is, if you have really good backups, perhaps automated versioned snapshots, then there is no need for any redundancy.
      There IS a need for redundancy as your "live" version of the data is not backed up.
      Redundancy gives you the oppertunity to back-up in between your normal backup schedule, if something fails.
      Of course, this also depends on how important your data is. If you can afford to loose it, then no need for redundancy, and probably no need for backup either.

      ryecoaaron wrote:

      I think raid5 can be a good thing when used on the right hardware. If you use cheap power supplies with old hard drives on a system that you put to sleep all the time (large percentage of OMV users), it doesn't make any sense. It makes even less sense when using arm boards with the drives connected to USB converters (another large percentage of OMV users). So, this is where the attitude comes from. If you are an experienced Linux user with good hardware then you aren't asking about raid and it doesn't apply to you.
      My last statement was probably a bit exhaggerated, Raid5, and several other Raid configurations are indeed not suitable for all types of scenarios and hardware.