Parity drive upgrade

[French-Guy]

 

Hello all,

I've read many different things (always with a slight variant actually) on how to replace my current parity drive (2TB) with a larger one, brand new (8TB WD red)

Is this the best method (assuming server is turned OFF):

 1) Remove current 2TB parity drive and install brand new 8TB drive (I'm using hot swap bay)

2) Turn server ON

3) Stop array (if auto started)

4) Assign new 8TB drive to parity slot 1

5) Start array

6) Parity should automatically start to rebuild without doing anything special, is that correct?

         *) How long should it take for a 8TB drive? My motherboard is SATA II "only"....I'm asking because my server shuts down automatically every night (12:30am) with a      command in the go file. So if the parity rebuilt is going to take quite some time, I want to make sure the server won't shut down before it's completed 

        *) Does the array remains available when the parity is being rebuilt?

7) Once parity is rebuild, should I do a parity check?

 

 

By the way, I'm using 6.6.5.................and I'm not planning to pre-clear (stress test) the new drive

 

Thanks

Edited November 19, 2018 by French-Guy

[Vr2Io]

8TB need at least 14hrs, there are no reason to let schedule shutdown active.

 

You may let array available. But if put it in maintenance mode during rebuild (array won't available) then old parity disk could still valid for add back in emergency.

[Hoopster]

My parity check with a single 8TB 7200rpm parity drive connected to MB SATA III port takes about 16 hours. Yours will likely take longer since it is a 5400 rpm drive.

 

Lower capacity data drives also tend to slow down parity checks. When my array was all 3TB drives parity checks took about 8 hours. Now that that all drives are 8TB the parity check is faster when comparing size to time.

 

Sent from my iPhone using Tapatalk

 

 

[John_M]

SATA III offers no performance advantage over SATA II with magnetic hard drives.

 

I personally would test any new drives before committing them to the array.

[French-Guy]

30 minutes ago, John_M said:

SATA III offers no performance advantage over SATA II with magnetic hard drives.

 

I personally would test any new drives before committing them to the array.

What is the best way to preclear in 6.6.5 then?

[John_M]

If you specifically want to preclear the disks then I believe the latest version of the Preclear plugin is compatible. However, you don't need a precleared disk for what you want to achieve, in the sense that using a precleared disk won't speed up the operation. I personally use the short SMART self test (to weed out anything damaged in transit and to mark the log with an event at zero power on hours) followed by badblocks in destructive write mode (-w option) to test new disks. It writes four different patterns of bits to the disk and reads them back, looking for write errors, read errors and comparison errors. I also use the -v and -s options so as to increase the verbosity and get a progress indicator, and large capacity disks seem to need the -b 4096 option too. So the command becomes:

badblocks -s -v -w -b 4096 /dev/sdX

where X is the identifier of the unassigned disk. I run it from the server console or from within a screen session so as to avoid the possibility of network disconnection as a 6 TB disk takes about four days to complete the four write passes and four read passes.

[French-Guy]

ok, I've installed the new 8TB red and parity is being rebuilt............0.4% right now (after 5 min)

I've put a "#" in front of the line shutting down the server at 1:30 am in the go file, so it will keep running

 

[JonathanM]

Just now, French-Guy said:

I've put a "#" in front of the line shutting down the server at 1:30 am in the go file, so it will keep running

At what point did you do that? The go file is only parsed at boot, so if you haven't rebooted after changing it, the line is still in effect.

[French-Guy]

I plugged the flash drive into my laptop and edited the go file (with notepad)

Then took the current 2TB parity out, and installed the new 8TB

And finally put the flash drive back in the server and started it up

 

[JonathanM]

👍

[French-Guy]

30 min.............................and 2%

It says approximately 22h34min left 😪

[JonathanM]

7 minutes ago, French-Guy said:

30 min.............................and 2%

It says approximately 22h34min left 😪

Sounds about right, depending on whether anything else is allowed to read or write to the array during the process, and the size and speed of the rest of your drives.

[French-Guy]

The data drives (4) are 3 x 1.5TB and 1 x 2TB

I will probably use the array tonight to stream a movie, but after that, nothing else until tomorrow night same time

[JonathanM]

After it crosses the 2TB line it will speed up a lot. Probably be done in 18 hours or so.

[French-Guy]

1h15min......................400GB 

"hang in there".........................................😂

[French-Guy]

Good morning,

4.52TB (56.5%) after 11h38min......6hr11min to go

But like you said, it's faster now (~155/160 MB/sec) when it was around 90 MB/sec at the beginning

 

Once the parity sync/data-rebuild is completed, should I do a parity check, or it's not necessary?

 

 

[JonathanM]

41 minutes ago, French-Guy said:

11h38min......6hr11min to go

Heh.

11 hours ago, jonathanm said:

Probably be done in 18 hours or so.

 

42 minutes ago, French-Guy said:

Once the parity sync/data-rebuild is completed, should I do a parity check, or it's not necessary?

If everything worked properly, it's not necessary. If you want to be SURE everything worked properly, do a correcting check and verify 0 errors.

[French-Guy]

I will check tonight when I come back home, but I assume the parity sync will be finished by then

My next question is about the former 2TB parity drive to be now used as a data drive...

Should I just install it, assign it and that's it?

Is there any specific thing to do first (pre-clear, formatting, etc?)

Thanks

 

[JorgeB]

2 hours ago, French-Guy said:

Is there any specific thing to do first (pre-clear, formatting, etc?)

You can preclear it, or just let Unraid clear it when it's added to the array, either way it will also need to be formatted after that.

[French-Guy]

OK, so old parity drive is now clearing.........it says 5 hours !

I really like the hot swap bays, it's so easy to switch/replace/add drives 😎

Edited November 20, 2018 by French-Guy

[trurl]

Be sure you take a backup of flash after these disk changes. It is especially important that your flash backup be up-to-date when you re-use a parity disk. More than one person has restored an old flash backup in this situation which made Unraid write parity to the old parity disk thus overwriting data.

 

You can always download a zipped copy of flash at Main - Boot Device - Flash - Flash Backup

[French-Guy]

I did a backup before installing the new 8TB

But I didn't do it again before re-installing the former 2TB parity drive though......!!!

[trurl]

4 minutes ago, trurl said:

Be sure you take a backup of flash AFTER these disk changes

You need your flash backup to know that the old parity disk is now a data disk or you could

5 minutes ago, trurl said:

restored an old flash backup in this situation which made Unraid write parity to the old parity disk thus overwriting data.

 

[French-Guy]

So you're saying once the clearing of the old parity drive is completed, I should do a flash backup?

[trurl]

Just now, French-Guy said:

So you're saying once the clearing of the old parity drive is completed, I should do a flash backup?

It is especially important after making any disk assignment change so if you need to restore flash it will boot up with the correct disk assignments.  But it is also a good idea to get a backup when you make any other change in the webUI since all webUI settings are saved to flash.

 

When it has finished clearing it will let you format the old parity as a new data disk. Wait until then to make the backup. Then the backup will know that disk is now a data disk and not parity.