6.5.3 Server upgrade - drive formats

[Anesthaesia]

Hi all,

 

I have recently upgraded from 4.7 to 6.5.3 - everything is working fine but I have a few questions about future maintenance regarding drive formats.

 

All drives are currently reiserFS. I have looked at the migration to XFS instructions but do not want to migrate all drives in a single operation. I would like to be clear about a few things:

 

1. Can ResierFS and XFS drives exist within the same array without problems?

2. I will be replacing some of the ReiserFS drives that have errors (and eventually all drives) - after preclearing a new drive and formatting with XFS, can I safely replace an existing drive and rebuild from parity?  ie. usual drive replacement process but moving from ReiserFS to XFS

3. If I replace the parity (currently ReiserFS) can I replace with an XFS formatted drive and rebuild the parity safely from existing ReiserFS drives and continue to use the drives with ReiserFS until I get around to replacing all?

 

The following can be assumed at any point:

1. Drives are the same size or larger than existing drives

2. Parity check is complete and error free

 

Thanks,

D

[bonienl]

1. Yes, ReiserFS and XFS can co-exist. Conversion can be done at any pace. No dependencies.

2. No, when replacing a disk for a new one, the resulting data rebuild is an exact copy of the old disk. Conversion is a separate action.

3. The parity disk does NOT contain a file system and works together with the data disks, regardless of the file system used on the data disks

 

Note: converting RFS to XFS means reformatting the disk. You need to copy the disk content first if you don't want to loose it.

Most  people follow these steps:

a. Copy disk X content to disk Y

b. Change file system of disk X to XFS

c. Format disk X as XFS

d. Copy disk Z content to disk X and repeat from step b (substitute X for Z)

e. Repeat steps b,c,d for all disks unitl done

 

[JonathanM]

5 hours ago, Anesthaesia said:

I will be replacing some of the ReiserFS drives that have errors (and eventually all drives) - after preclearing a new drive and formatting with XFS, can I safely replace an existing drive and rebuild from parity?  ie. usual drive replacement process but moving from ReiserFS to XFS

 

Just wanted to add emphasis to this.

 

NO. IF YOU REFORMAT THE DRIVE YOU ARE REBUILDING, ALL DATA WILL BE GONE.

 

Parity does NOT contain files or data. It can only recreate the entire drive as it is, file system and all. If you reformat the drive to a new file system, the data will be gone.

 

5 hours ago, Anesthaesia said:

I have looked at the migration to XFS instructions but do not want to migrate all drives in a single operation.

That's fine. You can follow the directions at your leisure and only migrate one drive at a time. The only requirement to start is that you have your largest single drive empty of files or fully backed up elsewhere so it can be reformatted to empty XFS. There is no rule saying you have to do all your drives continuously one after the other, you can do one then wait until you have time to do the next. 

 

[Anesthaesia]

Thanks both for the replies.

 

Based on the above and bonienl's steps, would the following work using a spare drive in an available server slot:

 

a. Preclear a new drive Y and add to array with XFS file system (excluded from all shares)

b. Copy files from X (ResierFS) to Y (XFS)

c. Format X as XFS

d. Copy data from Y (XFS) back to X (now XFS)

e. Unassign and remove Y

f. Rebuild parity

 

I assume that during the steps above, X could be replaced with a new drive at step c. if the existing drive had errors?

 

Writes to the server would be disabled during the conversion to ensure no issues with new data