I want to increase the capacity of my server. I have a number of 750 GB drives which I wish to replace with 1 TB and 1.5 TB drives. What I've done recently is:

 

Copy the data from two of the 750 GB drives to a single 1.5 TB. All three of these drives are in my array currently. I have no more vacant slots.

I want to remove BOTH 750 GB drives. I will replace them with higher capacity drives in my case.

I understand that if I start the server, it will not start the array because two disks will be missing.

 

I just want confirmation of the following:

At this point I could "Trust my array" the server and get it to restore and calculate parity based on the array with the two missing disks (since the data is already on the 1.5 TB drive, everything is intact).

I assume that, while parity is being calculated, I could use the preclear script on the two drives I replaced in my case.

When parity is redone, and the drives are cleared, I could add them to the array also.

I can then repeat this process twice more and finally be rid of my hot-running, low capacity 750 GB drives.

I'd only need to recalculate parity three times this way, rather than six times if I rebuilt the data one drive at a time the conventional way.

 

Are my assumptions correct, and if so, would you experts caution against doing the parity calc and preclear on two drives simultaneously. If it makes a difference, I'm running a celeron 420 and 2 GB ram.

 

Thanks very much to anyone reading/replying.

I want to increase the capacity of my server. I have a number of 750 GB drives which I wish to replace with 1 TB and 1.5 TB drives. What I've done recently is:

 

Copy the data from two of the 750 GB drives to a single 1.5 TB. All three of these drives are in my array currently. I have no more vacant slots.

I want to remove BOTH 750 GB drives. I will replace them with higher capacity drives in my case.

I understand that if I start the server, it will not start the array because two disks will be missing.

 

I just want confirmation of the following:

At this point I could "Trust my array" the server and get it to restore and calculate parity based on the array with the two missing disks (since the data is already on the 1.5 TB drive, everything is intact).

I assume that, while parity is being calculated, I could use the preclear script on the two drives I replaced in my case.

When parity is redone, and the drives are cleared, I could add them to the array also.

I can then repeat this process twice more and finally be rid of my hot-running, low capacity 750 GB drives.

I'd only need to recalculate parity three times this way, rather than six times if I rebuilt the data one drive at a time the conventional way.

 

Are my assumptions correct, and if so, would you experts caution against doing the parity calc and preclear on two drives simultaneously. If it makes a difference, I'm running a celeron 420 and 2 GB ram.

 

Thanks very much to anyone reading/replying.

You CANNOT use the "trust" procedure with ANY missing disks.  Therefore, to try it with two missing disks will not work as intended.  It might be possible for you to convince the server to not perform a parity sync, but parity will be wrong. (Any you will be thinking you can restore from a disk failure, but will be unable.)

 

There is ONE exception to this rule... and that is to perform a special "zeroing" of a drive while it is in the array, setting all bits in it, including its formatting, to zero.  Once zeroed, you can remove it wiithout affecting parity. (and use the "trust" procedure)  Note that this is not the same as what you were doing (deleting the files on the drives only deletes the directory entries, and most of the bits on the disk are unchanged)

Read this thread to see how: http://lime-technology.com/forum/index.php?topic=2591.msg20919#msg20919

Ask questions if un-sure...  There is no un-do if you zero the wrong drive. 

 

A far easier method would be to copy your data from the two 750 Gig drives to the 1.5Gig drive, then stop the array and un-assign the two 750 Gig drives.

Then go back to the main management page and press the "Restore" button.  It is very poorly labeled, and it is actually a "set initial disk configuration" button.  It will set your configuration to one without the 750 Gig drives.  When you press the "Restore" button you will be without parity protection until a full parity calc is completed. When you then "Start" the array it will then start a full parity calculation on the remaining drives (those still assigned) in your array.  When the parity calc is complete, you will be protected from a disk failure once more.

 

After that parity calc is complete, you can stop the array, power down, and remove the two old 750 Gig drives.  Using the "Restore (Set Initial configuration) button will allow you to remove your two drives in one step and re-calculate parity only once.

 

You can pre-clear any disk that is not assigned to your array, so once you un-assign the 750 Gig drives and press restore you can use the pre-clear script on the old unassigned drives to erase any old data on them.  I'd wait until parity calculation is complete, that way, you have a copy of your old data on them just in case the new 1.5TB drive fails while parity is being calculated initially.

 

Joe L.

Apologies, Joe L. It was late when I created the thread. I didn't mean to say "trust my array"; I meant "Restore" as you said. I should have thought more carefully about what I was writing.

So what I meant was a way to tell unRAID that it's okay, the missing disks are deliberate. Thanks for the info on unassigning the disks first - that I would have missed, and your procedure is a much cleaner way of doing it. There's one modification I'd like to ask about:

 

After unassigning the disks can I:

Shut down,

Replace the drives in my case

Restart the server

Restore the array as described above (without assigning the new drive(s))

While the new parity calc is going on, clear the new drive(s) at the same time.

?

 

To be clear, the data on the two 750 GB drives has already been copied (and is now duplicate data on the 1.5 TB drive). I was never going to clear/zero the 750 GB drives that are destined to be removed. One of the beauties of unRAID is exactly that if something went wrong I could add these drives back into the array and recover my data. Therefore I was going to wait until all the upgrades were over and then use the 750s in another computer, reformat them to ntfs etc.

 

Thanks again, Joe L.

 

Yes, do as you described. You can use <alt> F1 - F6 (I think it's <alt> key) to get to different login windows or just telnet twice so you can do two preclears at the same time.

 

Once parity is calculated and the 2 new drives are precleared then stop and add them. I think you will get a checkbox under the start button you have to click first before starting the array but then you might be able to just start. I'm not sure about adding multiple drives at once so you might just want to add one drive and start and then stop and do the next drive. In either case it'll just take seconds to add the drives.

 

Peter

Thanks, Peter. FYI, I've added multiple drives before, and iirc, it's no problem. I'll post here if my experience is otherwise.

 

[EDIT - addendum]

Thanks everyone - right now, parity is being recalculated and two drives are being precleared. I'm at work, so hopefully everything will continue to chug away successfully while I'm away. Should all be done by Sunday or late tomorrow.

All done, no particular problems except that for a few hours, the parity calc was running at 1 MB per sec or so. I seem to recall that happening last time too, so I'm wondering what's up. After the 1 TB stage it sped up significantly. Also, no problem formatting and adding two cleared drives to the array at the same time.