Gary

... although just to be clear, you'd only need to buy TWO of the 6TB drives to start -- that would give you 6TB of protected storage.

 

 

Garycase-So I build up the system, but only have a single 2TB drive in it.  I am waiting for a 4TB WD Green that I ordered for the parity drive to arrive in the mail.  Can I start it up with unRAID and play around, or will it have issues with only 1 drive present?  I just want to see a) all the other components are working properly, and b) the unraid interface and maybe general settings.  Obviously disk set-up and starting to add files to the nas will have to wait until my parity drive arrives...

You can run unRAID without parity protection, adding parity later. I would want to have an onsite and offsite backup in this case.

As noted, you can simply assign the one drive you have as a data drive and go ahead and start using UnRAID.    It will work fine -- in fact, writes will be a lot faster than they're going to be after you add the parity drive (since it takes 4 disk I/O's to write a sector to preserve fault-tolerance after you add parity).    But, as also noted above, that means your UnRAID system won't be fault tolerant, since you don't have a parity drive installed ... so backups are even more important.

 

But it's fine to "play" with it ... and it's actually a good time to load your data on it, since the writes will be 2-3 times as fast as they will be with parity installed.

 

Awesome - thanks!  I didn't realize I could also load data - that's a big plus.  But it will remain resident on my HTPC as my backup so if the solo drive fails, it can just be replaced.  Thanks again - look forward to messing with it.

Technical question... To end a telnet session in Windows, do I just click the x on the window? Or is there a command? I tried 'quit'  but it came back with '-bash: quit: command not found'

 

As a side note, running my first preclear! Also got email set up (nice feature!)

The command to end the session is "exit" 

 

Assuming you ran a command prompt to use Telnet, then you need to type a 2nd "exit" to close the command prompt window.

 

OK. Thanks!

You can end a telnet session by typing 'exit' (rather than 'quit').  Whether that will close the telnet app window depends on the app being used.  I normally just hit the 'x' as that is guaranteed to both end the telnet session and close the window.

Technical question... To end a telnet session in Windows, do I just click the x on the window? Or is there a command? I tried 'quit'  but it came back with '-bash: quit: command not found'

 

As a side note, running my first preclear! Also got email set up (nice feature!)

Try

exit

Technical question... To end a telnet session in Windows, do I just click the x on the window? Or is there a command? I tried 'quit'  but it came back with '-bash: quit: command not found'

 

As a side note, running my first preclear! Also got email set up (nice feature!)

Since nobody said anything, I feel obligated to speak up. Unless you started a "screen" session and ran the preclear inside of that, closing the telnet window stops any foreground process in that window, which would end the preclear prematurely. You didn't mention your exact process, and didn't say you had a running preclear in the telnet session you closed, but I put the two together anyway. My apologies if I'm telling you something you already figured out from searching.

Jonathanm brings up a good point ... you didn't say what you were using the Telnet session for; but if it was to start a pre-clear,  you have to leave it open until the pre-clear finishes.  Much better to either use Screen, or to simply do it from the server's console (if you have one).

 

On the other hand, if you were just using Telnet to do some other functions (e.g. loading UnMenu), then there's no problem closing it when you're done.

 

This was purely telnet for fun. I do have screen which I used (am using)  for the preclear. I have no problem getting out of that (alt-a, d) and now exit works to wrap up telnet after that. Thanks all.

Now for a security question, I have two wires connected to my unraid box, a power cord and an eternal cable plugged into my wireless router. Even thought it's plugged in, is it secure? Noone outside my network on the internets can access it? Or do I need to do any settings to protect this.

Now for a security question, I have two wires connected to my unraid box, a power cord and an eternal cable plugged into my wireless router. Even thought it's plugged in, is it secure? Noone outside my network on the internets can access it? Or do I need to do any settings to protect this.

If your unraid has a private IP address, your router isn't forwarding any ports, and you aren't running any addons that activate uPNP, then you are as secure as you need to be.

OK. Looks like I am good by default then. Thanks!

Next question - preclear.

 

So I am running a preclear on a 2TB drive right now - looks like it will take about 2 days and change.  Brand new drive.

 

I plan to use a 4TB drive as a data drive the I have been using for a little over a year now.  Should I run preclear 3 times on that drive as well, or just once.

 

What is the advantage of 3 vs 1 run of pre-clearing?  I am getting a new 4TB drive (to be the parity drive), and I would rather just run one pass (~1 day) rather than tie it up for three days...but what could I lose?

 

I am running this in screen btw.

 

I've had drives fail on preclearing cycles 1, 2, and 3.  I recently precleared 3 4tb Seagate 14 times, as my friend that bought them wasn't around to have them installed for a couple months.

 

I usually do 5 cycles.

5 cycles!  Wow.  How long did the 4 TB take to do that?

 

So what happened if you only run one cycle?  What do you mean by you found out the disk was 'bad'?  Will the whole thing die?  Or does it only restrict the useful size of the disk?

I've only ever done the 14 cycles on 4tb and I can't remember how long it took as I just looked at the reports to see if there were issues - there weren't.

 

If I have problems with a brand new disk (pending sectors, reallocated sectors) on a disk, I RMA it.  Those issues really shouldn't show up on a brand new drive.

 

The problem with running only 1 cycle is that it may not find the problem.  I can personally attest to this due to the fact that I've had drives completely die on pass 2 of preclear (start clicking, unable to read), and another drive develop over 1000 bad sectors, on pass 3.  Neither of these should happen on new drives.

 

There is a bathtub curve http://en.wikipedia.org/wiki/Bathtub_curve associated with hard drives.  Many drives will fail in the beginning of their life cycle, then the majority of the remaining drives will be fine for a long period of time, and then many will die at the end of the life cycle.  By checking every sector of the drive multiple times, you know the sectors are likely reliable (or were).  Without checking them you don't know. 

I'm sorry... I don't think I understand. You say you've only ever done 14 cycles on 4tb drives? As in weeks of preclear time? You have a good point... I'll run 3 cycles on my new drives, but just 1 of  my old drives that have been used for over a year.

I'm sorry... I don't think I understand. You say you've only ever done 14 cycles on 4tb drives? As in weeks of preclear time? You have a good point... I'll run 3 cycles on my new drives, but just 1 of  my old drives that have been used for over a year.

 

Yes, it took a long time. The drives were for a friend that wouldn't have time to install the drives for 2 months so we figured why not?

OK. Thanks. I think I've got my preclear plan in place then. Is there any way to pause a preclear? For instance, if you're a week into your 14 cycle preclear and want to add another disk and start to preclear that simultaneously (shut down unraid box, install disk, restart box required)  is it possible? Or do you have to wait for the first  preclear to finish first?

OK. Thanks. I think I've got my preclear plan in place then. Is there any way to pause a preclear? For instance, if you're a week into your 14 cycle preclear and want to add another disk and start to preclear that simultaneously (shut down unraid box, install disk, restart box required)  is it possible? Or do you have to wait for the first  preclear to finish first?

Short answer to the direct question, no, you cannot pause a preclear.

 

Long answer for the question you meant to ask, but didn't know. Only the write portion of the preclear actually does anything that matters to unraid, and that part only matters if you are adding the disk to an already parity protected array, it just saves the time unraid would take to write all zeroes to the disk to be able to add it without breaking parity. The reason most of us run preclears on disks, many times multiple passes, is to ensure the disk is healthy before we rely on it to protect our other disks. You see, with unraid, ALL the disks are used, in their entirety, to rebuild any single failed drive. So unlike most computer applications, we have to be confident that the entire disk is good, not just the little bit that we are going to use. Many times disks that would have been perfectly happy to be used for years in a windows machine fail when asked to perform in an array. Preclear reads and writes the entire disk, and asks the disk for a smart report to see how it's doing. It compares the initial smart report with the one it pulls after doing a full cycle, and compares them to point out any differences. If the drive happily does a couple (or more) full capacity reads and writes, you can be more confident that it will perform when asked in your array. The more cycles you do, the more confidence you can have, up to a point.

 

Since the only cycle that counts is the last one for the purposes of adding the drive to an already protected array, you can stop a preclear whenever, and start a new one when it's convenient. Drives that are going to be used as replacement drives, or in a totally new array don't even have to complete a cycle to be used. It's just a good workout for the drive.

That makes a lot more sense. Thanks for the time for the detailed explanation. I do have one follow up... You said all drive are used in their entirety to rebuild a single failed drive. Why? In my simplified view, if you have 3 1tb disks (1 of which is parity) and a total of 1tb worth of data, I would imagine each data drive with 500gb and the parity drive half full of parity and half full of zeroes. If a drive failed, wouldn't only half of the remaining two disks be required to rebuild the array with whatever new third disk is added?

 

A curiosity question that I don't plan. You said I could stop a preclear whenever and restart it when ready. How do you stop it?

 

Finally, to learn more.. You said preclearing is only really required to add to an existing array which makes sense for the parity to be unchanged. However, for a brand new array if you don't preclear, would that cause any errors later on since the information would be random? Or does unraid always calculate the parity for data as it is added and the remainder of the party drive doesn't matter?

 

Hopefully these questions make sense. Thanks for the help!

When you rebuild a disk, the entire contents of the disk is reconstructed on the new disk -- even if it's all zeroes.  How much data is actually on the disk is completely irrelevant.

 

For a new array, it makes no difference if a disk is pre-cleared or not -- as you noted, the contents may be random, but it doesn't matter.    In that case, pre-clearing is simply useful as a confidence test of the disks.