Is it possible to disable the parity check completely on dirty shutdown?

[theruck]

i am talking about real data integrity, not about what the system can or cannot expect based on its own or any other technical limits

but as you said it cannot know if it is true or false so its a most of the time wrong guess

 

[whipdancer]

21 hours ago, theruck said:

the vendor is overlooking the fact that this behaviour should be configurable because

No, it really shouldn't be. The premise of the OS is to protect your data. Turning off this behavior turns off the ability of the system to know to check if the data is protected.

 

Quote

i have proof that the vendor is 100% of the checks wrongly assuming the parity is not in tact.

You don't have proof. You have anecdotes about how your system behaves. That is not the same thing as proof that parity checks are not necessary.

[theruck]

1 hour ago, whipdancer said:

Turning off this behavior turns off the ability of the system to know to check if the data is protected.

that is of course not true. The system does not know anything about your data or parity validity. It only guesses it and that is the problem

you have not understood anything from this topic

1.  i need it configurable not disabled

2. the data is still in tact

3. the OS does not premise nor guarantee you anything.

And i have statistically and technically proven that my use case does not corrupt data while you have no argument against only theoretical BS about non-existent data protection.

[Squid]

This debate is really no different than if on a Windows box a loss of power happens during sleep if Hybrid sleep is not enabled (can only be done via Control Panel).  Data loss and corruption can / will occur

 

Plus, it has to be noted that Limetech does not even support Sleep in the first place.  This functionality is via a 3rd party plugin.

 

No matter how you cut it, the loss of power results in an unclean shutdown.  Not really any debate about that.  And if/when data loss results from the unclean shutdown and if it was possible to disable the automatic check then are you going to blame yourself or are you going to wind up blaming the OS?

 

That being said your options are the following either install a UPS (should be done anyways on any and all electronics in your house regardless) or stop the parity check from continuing that results.

 

Something like this via User Scripts set to run at first array start

#!/bin/bash
sleep 300
/usr/local/sbin/mdcmd nocheck

 

[theruck]

thanks that could actually be quite nice solution

anyway it is not comparable with windows as windows does not have a journaled filesystem (other than ReFS)

how hard would it be for limetech to enable this thing to be configurable? run parity check automatically on reboot after dirty shutdown - YES/NO

i am pretty sure there are other situations like when you have a failing drive that you dont want to do the parity check immediately especially when you have a dying drive which you do not want to overheat before you save the data etc.

 

also i believe that the already existing checkbox to write parity corrections is much more dangerous to the user data than the checkbox to disable parity check on dirty reboot would be. this checkbox cannot be unchecked on my system (its always checked after every reboot) so if i have a failing data drive the parity will be overwritten with wrong data after a dirty reboot

[theruck]

by the way you guys seem to not know this

 

if you have a dirty reboot and the parity check starts

 

then you do a CLEAN REBOOT of the system before the parity check finishes

next reboot you get a miracolous Parity is valid!

 

So much for all the suggestions and BS about UPS and clean shutdowns and how Limetech cares about your data.

As i stated in this topic its all a very unqualified and primitive guess that the parity needs a check and in situations when it actually needs a check it either does not think it is needed or overwrites your correct data with data from a failing parity drive without any notification to you, users.

Edited October 21, 2022 by theruck

[itimpi]

3 minutes ago, theruck said:

then you do a CLEAN REBOOT of the system

next reboot you get

I would consider this as a bug.    The system should remember that parity was not considers valid at the point the system was shut down.   It sounds as if the marker file that is used to indicate an unclean shutdown is being deleted too early.

[theruck]

well then i live with this bug

[whipdancer]

On 10/21/2022 at 9:29 AM, theruck said:

i have statistically and technically proven that my use case does not corrupt data

Actually, you haven't statistically proven anything. You've provided plenty of anecdotal evidence of your experience.  Those are not the same thing.

[dev_guy]

On 10/18/2022 at 11:19 AM, theruck said:

my use case is that the server is being used only few minutes maybe hour a day and then the server sleeps. then as it sleeps its power is turned off. so its considered dirty. technically its not as the drives are spun down anyway. so it boots and starts parity check which never ends because it takes so many hours and the process repeats anyway. so the parity check preserves the server from sleep because it is active and i want it

to be sleeping when inactive. 

I would suggest using a NAS that officially supports sleep. You are trying to make Unraid do something it was never intended to do. Popular commercial NAS systems from companies like Qnap, Synology, etc, have native support for sleep because, unlike Unraid, they control the hardware, BIOS, etc. You can use a Wake On LAN packet to wake a Qnap or the power button on the front. You can also set up a power schedule for it to automatically sleep and wake one or more times a day if you like.

 

Unraid doesn’t have that kind of functionality because Unraid is hardware agnostic and, as you have found out, some motherboards don’t support S3 sleep in a compatible way with Unraid. Yes Unraid could add a way to disable parity checks for unclean shutdowns but I have to agree with everyone else you simply shouldn’t be doing unclean shutdowns in the first place with any file server not just Unraid. Any decent file server is going to want to run a file system/parity check on a dirty shutdown.
 

If you care about your data, you should buy even an inexpensive UPS. They start around $40 US for decent ones with USB support to prevent dirty shutdowns. I understand your view if the server is already in the sleep state the data on the drives cannot change even if the power is turned off. But the server has to do a cold boot from an unknown state. You asked for a solution to your problem and it sounds like a UPS is a solution, and is considered wise for any file server/NAS, especially if your power is interrupted as frequently as you suggest. 
 

Further many do not realize SSDs can be badly corrupted from power interruption even when they’re not being written to at the time as SSD’s are often performing housekeeping write tasks like TRIM on their own. Most only have, at best, partial power fail protection in their firmware. Any system, not just servers, with data you care about should be on a UPS or, for laptops, have at least a partially charged battery especially if you have known power problems. 

What you want is analogous to when the Low Oil Check Engine Light in your car comes on. You want a way to just turn the light off, never check the oil, and just keep driving. No car maker is going to offer that “feature” as you could easily damage your engine. 

 

[theruck]

54 minutes ago, dev_guy said:

Unraid doesn’t have that kind of functionality

its kernel functionality and as you already know with the S3 sleep plugin the sleep is possible and used by hundreds of users so it is well tested as well

55 minutes ago, dev_guy said:

solution to your problem and it sounds like a UPS is a solution

you understood nothing from this topic but that is your shame not mine

56 minutes ago, dev_guy said:

unclean shutdowns in the first place with any file server not just Unraid.

we are in 2022 and it has been many many years since any modern filesystem does not get corrupted with dirty shutdowns.

 

57 minutes ago, dev_guy said:

SSDs can be badly corrupted from power interruption

not during machine sleep.

 

58 minutes ago, dev_guy said:

No car maker is going to offer that “feature” as you could easily damage your engine.

No car maker is going to call your car to the service once your oil light has come on for a second - inadequately assuming that your engine is corrupted - this is what unraid does today with our parity.

 

wake up man you are full of nonsense this is about parity check not about data integrity on the filesystem. you probably do not understand the topic but your parity even when your servers are on UPS are not any cleaner than mine is after the dirty shutdown. you know the parity quality only after the finished check and since that moment you can have corrupted parity due to failing drive or memory module so you really need to get your stuff together before posting such BS