Removing multiple drives

Sorry for the long post

 

My questions arise from the fact I need to make some changes before I migrate to ver. 6. I am currently using out dated hardware, including old,  ATA IDE drives. With new hardware on the way I need to solve the problem created by these drives.

 

First, I will ask my questions and then present my plan of attack for removing the outdated drives. Help/advice will be appreciated.

 

Questions

I plan on using Limetech's method for removing a drive but, before I start I would like some clarification on using the New Config utility.

 

1. I'm not sure what it actually does, and how it relates to previous array assignments.

 

2. Also, are there there any options in using this utility that I should be aware before it is invoked?

 

Plan of attack

 

I want to replace two 500GB drives with a 1 TB drive. The steps I plan to take unless the experts suggest otherwise are:

 

1.I have precleared the drive and now ready to assign it to the array.

 

2. Next I want to copy the contents of the two smaller drives to the larger one.

 

3. From Maintenance mode execute Limetech's command "dd bs=1M if=/dev/zero of=/dev/md3  <-- 'md3' here corresponds to 'disk" (ID  to remove)

 

4. Execute New Config utility

 

5. "Go back to Main, assign Parity, and all devices except the one you just cleared."

 

6. "Click checkbox "Parity is already valid.", and click Start"

 

7. Repeat steps 3-6 for the removal of second drive.

 

 

New Config clears all drive assingments and your parity.

 

When you press the button, you'll need to assign the disks again and create a new parity.

 

I suggest you run parity check before to make shure the data is intact. When you press New Config the new array will not be protected until parity is created again.

New Config clears all drive assingments and your parity.

 

When you press the button, you'll need to assign the disks again and create a new parity.

 

I suggest you run parity check before to make shure the data is intact. When you press New Config the new array will not be protected until parity is created again.

Not entirely correct. It invalidates all the drive assignments, but doesn't alter any contents. So, if you have fully zeroed the drives you are removing, parity should still match and won't need to be recreated, just checked.

 

Just be VERY careful with the dd command to zero your drives, it is next to impossible to recover data erased that way.

 

If you zero both drives you wish to remove, you can remove them both at once instead of repeating the steps.

 

Be VERY careful assigning a drive to the parity slot, I'd personally have someone watching over my shoulder and following a guide showing which serial number went where.

Thanks, These two post were very helpful.

 

Be VERY careful assigning a drive to the parity slot, I'd personally have someone watching over my shoulder and following a guide showing which serial number went where.

 

I have a hard copy of the assignments plus each drive is marked with its sn and assignment no. Should the drives be assigned following their old position? I thought they should but was wondering about the hole left by the removed drives.

 

If you zero both drives you wish to remove, you can remove them both at once instead of repeating the steps.

 

Thanks, that will save me some time

 

Just be VERY careful with the dd command to zero your drives, it is next to impossible to recover data erased that way.

 

I plan to copy and paste from Tom's post and then do a visual check

 

 

Just be VERY careful with the dd command to zero your drives, it is next to impossible to recover data erased that way.

 

I plan to copy and paste from Tom's post and then do a visual check

Just so long as you understand the meaning of what you are typing. If you blindly copy, you will probably end up erasing the wrong drive. Which slots are you planning on removing?

Just so long as you understand the meaning of what you are typing. If you blindly copy, you will probably end up erasing the wrong drive. Which slots are you planning on removing?

 

The drives are identified as "sda" and "sdb." The command I would use for "sda" is:

 

dd bs=1M if=/dev/zero of=/dev/sda

 

for "sdb" is: dd bs=1M if=/dev/zero of=/dev/sdb

 

In responding to your post I noticed the array uses "sda" and "sdb" to identify these drives. However, I think i read somewhere that these drives would be identified using "hda" and "hdb".

I know these drives are old parallel drives so why are they being identified as they are. Am I giving this the wrong interpretation? Now I am not sure as to what is going on.

 

 

Now I am not sure as to what is going on.

Ok. So, at this point, you need to get your head around what you are trying to do. If you blindly follow stuff meant for other people, you will lose data and mess yourself up. First, sd? or hd? designations can change when you reboot, so using that to identify which drive you want to operate on is a recipe for trouble. Second, if you don't yet understand why you are writing zeroes to the drives, you shouldn't do it until you understand why it matters, or if it is really worth the risk of zeroing the wrong drive.

 

Do you have backup copies of your important data?

Also, using sd or hd would both be incorrect for the intended purpose. The example in the OP uses md for a very good reason, to maintain parity.

Guys, thanks for the advice and warnings. I'm glad you responded to my post. This is my first time doing this and I might have been in big trouble. I know enough to be dangerous. 

 

First, sd? or hd? designations can change when you reboot, so using that to identify which drive you want to operate on is a recipe for trouble.

 

I did not know this. Anyway the drives I want to remove are at positions 2 and 4. I guess I need to use these positions instead at the time of writing zeros to them? Also, are you saying the PATA drives could have either a sd or hd desgination?

 

Also, using sd or hd would both be incorrect for the intended purpose. The example in the OP uses md for a very good reason, to maintain parity.

 

So it should look like this?

 

d bs=1M if=/dev/zero of=/dev/md2  (md4)

I actually came up with this idea years ago and it works quite well. Zeroing 2 of them will slow you down as you should not try do do them in parallel. Many fear the command line so here is a not quite as good way I'd recommend if the zeroing option is too scary.

 

Insert the new drive (whatever physical disk swapping gets done first), do a parity check (always a good idea before doing array disk rearranging to make sure you are starting from a solid foundation), copy all of the data to the new disk, then do your new config, assign the drives as you like, and build parity. You are at risk for a drive failure during the rebuild but immediately after a parity check the odds are way in your favor. The two drives you are replacing stay intact as backups.

Thanks, to all who posted. This advice, as well information from other threads, enlightened me as to the advantages ver. 5 has over ver 4. I never paid attention to this and upgraded to keep current. Therefore, I was looking at this from a ver. 4 perspective. All questions I had have been answered. I will be using the command line to remove the drives.

 

Thanks for the help in clearing this up.