question regarding parity


CSIG1001

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Drives are dying no matter if you are using a UPS or not. In my experience in the past i saw it a couple times that more than one drive from the same order/series died in a couple weeks or months from each other. Keep in mind, parity/raid is no backup. Always backup your data somewhere else in case of a hardware failure and don't rely on a parity drive. I only have 3 drives, one of them as parity and currently i don't need more space. I have another NAS from Synology where i backup my data to and from that i backup my data to an extra external drive. I can't really give you a recommendation on how to set up your parity. It's up on you. For safety reasons i would say go for the 2 drive parity.

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3 minutes ago, bastl said:

Drives are dying no matter if you are using a UPS or not. In my experience in the past i saw it a couple times that more than one drive from the same order/series died in a couple weeks or months from each other. Keep in mind, parity/raid is no backup. Always backup your data somewhere else in case of a hardware failure and don't rely on a parity drive. I only have 3 drives, one of them as parity and currently i don't need more space. I have another NAS from Synology where i backup my data to and from that i backup my data to an extra external drive. I can't really give you a recommendation on how to set up your parity. It's up on you. For safety reasons i would say go for the 2 drive parity.

 

i understand backups

 

but i have 190tb  which is no in my budget to pay for more tb space to back it up, and i think i will be fine with  2 parity unless my house burns down or i get robbed. Also from my understanding data only reads off one drive so i am sure my drives will be fine especially when they are all WD reds..     

Edited by CSIG1001
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4 hours ago, CSIG1001 said:

 

i understand backups

 

but i have 190tb  which is no in my budget to pay for more tb space to back it up, and i think i will be fine with  2 parity unless my house burns down or i get robbed. Also from my understanding data only reads off one drive so i am sure my drives will be fine especially when they are all WD reds..     

Sorry to be blunt, but that is a very naive approach. You say you understand backups but you are not prepared to spend the money on them. The only possible conclusion is that you place little value on your data. That's your choice and that's fine and one of the great things about Unraid is the fact that the data is not striped across the disks, so in the event of a catastrophic failure any surviving individual disk can be plugged into a Linux box and the data read from it.

 

WD Reds are decent enough but they are still mechanical devices that are built to an affordable price. They will fail - that's guaranteed. Any other component in your server can fail and in some cases the failure can be catastrophic - an example being the power supply.

 

If you really have 190 TB of data then an awful lot of it must be archived away and seldom accessed. Perhaps that makes it less important? At the very least you should backup what you consider to be irreplaceable.

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2 hours ago, John_M said:

Sorry to be blunt, but that is a very naive approach. You say you understand backups but you are not prepared to spend the money on them. The only possible conclusion is that you place little value on your data. That's your choice and that's fine and one of the great things about Unraid is the fact that the data is not striped across the disks, so in the event of a catastrophic failure any surviving individual disk can be plugged into a Linux box and the data read from it.

 

WD Reds are decent enough but they are still mechanical devices that are built to an affordable price. They will fail - that's guaranteed. Any other component in your server can fail and in some cases the failure can be catastrophic - an example being the power supply.

 

If you really have 190 TB of data then an awful lot of it must be archived away and seldom accessed. Perhaps that makes it less important? At the very least you should backup what you consider to be irreplaceable.

 

I will be backing it up but not daily and once the data is written and the drive is full it will be only used to read and will most likely not be left on all the time. Its a plex server , and I have been running a JBOD  for about 5 years with no issues for plex .

 

Btw you seem like you been on the unraid forums for awhile monitoring peoples experience with unraid , how many have completely lost data with  a 2 parity setup?  If so what was the cause ?

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I know of two instances in recent years when users destroyed all their hard drives simultaneously. One was caused by the use of incompatible modular power supply cables and one was caused by a Molex plug being forced into its socket the wrong way round. Both human errors and both avoidable. Both happened when the users upgraded their hardware. It's a very tempting short-cut to replace the power supply but reuse the existing cables.

 

The modular power supply problem is very real and I have to be constantly aware of it myself. I build a lot of computers - most of them not Unraid servers - and I have standardised on three types of power supply: the Corsair RM650x for general use, the Corsair AX760 when I need a bit extra, and the Corsair SF450 for mini ITX builds. Despite being the same brand, the AX has cables that are incompatible with the RM and SF, though the latter two are interchangeable (which is handy because the SF ones are shorter than the RM ones). The AX cables are labelled at the PSU end but I keep the spares in two separate boxes to be certain of not mixing them up.

 

The Molex connector is a dreadful design with pins made from folded thin sheet metal which can be quite difficult to mate the correct way and not much more difficult to mate the wrong way. Often very soft plastic is used which makes it disturbingly easy to get wrong.

 

Less extreme examples include people destroying a backplane's worth of drives in one go, so not the end of the world, thanks to the way Unraid doesn't stripe data, but not exactly a fairytale ending either.

 

You don't need to mess up the hardware to lose data though. Something as simple as

!!DO NOT TYPE THIS!!

rm -r /*

will delete everything. You see, backups don't just protect you from disk failures. They protect you from yourself - or, at least, they give you a second chance to get it right.

 

I wouldn't expect daily backups - that would be pointless, especially since the vast majority of your files never change. But that fact alone makes it very easy to do backups using rsync. Once you have your initial backup rsync will subsequently only send the changes, making regular backups much quicker. You can exclude folders that can be easily replaced. For example, if you have a box of DVDs and Blu-ray discs, you might decide that it's preferable to rip them again instead of backing up the .mkv files.

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Thanks for the info 

 

you seem to know alot about unraid  and how it works.

I do not plan on typing any commands in linux

i do plan on backing up to spare drives every few years 

 

I do have newer power supplies gold evga  800+ watt

 

and i am pretty sure i will not mess up my backplane by inserting the molex backwards ,   I am using a cheap 24 bay norco with the updated backplane and sas connections

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10 minutes ago, CSIG1001 said:

i am pretty sure i will not mess up my backplane by inserting the molex backwards

Lol! And I'm pretty sure the other guys were pretty sure they wouldn't screw it up either :) I mean, nobody begins a project with the intention of getting it wrong. The best you can do is be aware of the pitfalls, listen to advice and take things slowly.

 

I strongly suggest that you test your new build with a single drive before committing your 190 TB archive to it. Preferably use an old one that still works but isn't part of your array. Use it to test every slot, just in case. Backplanes occasionally have faults too.

 

I'm not really familiar with EVGA power supplies but they are probably pretty decent. The important thing for a file server with many disks is to provide those disks with the current they need when spinning up. I only ever use PSUs that have a single high current +12 volt rail. If you don't then you need to make sure the disks are split roughly evenly across the available rails, to avoid overloading any one of them. Single-rail PSUs are very strongly recommended for an Unraid server but choosing a well known brand name doesn't guarantee that you're getting one. Split rails don't adversely affect a typical gaming build or office PC in any way - it's really only an issue for a build that uses a lot of magnetic hard drives. If you're unsure about your particular model then check on EVGA's web site or post the exact model number here.

 

A couple more examples of catastrophic failures come to mind. One user knocked his tower over and caused multiple head crashes on disks that were active at the time. I'm sure others have had shelves collapse and wreak similar havoc. Also, servers are sometimes destroyed by floods - probably more common where they're kept in basement rooms. So there are a lot of situations where parity offers no protection at all.

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6 minutes ago, John_M said:

Lol! And I'm pretty sure the other guys were pretty sure they wouldn't screw it up either :) I mean, nobody begins a project with the intention of getting it wrong. The best you can do is be aware of the pitfalls, listen to advice and take things slowly.

 

I strongly suggest that you test your new build with a single drive before committing your 190 TB archive to it. Preferably use an old one that still works but isn't part of your array. Use it to test every slot, just in case. Backplanes occasionally have faults too.

 

I'm not really familiar with EVGA power supplies but they are probably pretty decent. The important thing for a file server with many disks is to provide those disks with the current they need when spinning up. I only ever use PSUs that have a single high current +12 volt rail. If you don't then you need to make sure the disks are split roughly evenly across the available rails, to avoid overloading any one of them. Single-rail PSUs are very strongly recommended for an Unraid server but choosing a well known brand name doesn't guarantee that you're getting one. Split rails don't adversely affect a typical gaming build or office PC in any way - it's really only an issue for a build that uses a lot of magnetic hard drives. If you're unsure about your particular model then check on EVGA's web site or post the exact model number here.

 

A couple more examples of catastrophic failures come to mind. One user knocked his tower over and caused multiple head crashes on disks that were active at the time. I'm sure others have had shelves collapse and wreak similar havoc. Also, servers are sometimes destroyed by floods - probably more common where they're kept in basement rooms. So there are a lot of situations where parity offers no protection at all.

good idea i  have heard of doing that for each bay before putting in all the drives into the backplane..   oh yeah i will make sure the power is split between the cables

thanks again!

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