I came across that and tried it - the short answer is no, you can't do that - using cache tier. The longer answer as to why I'm less sure about, but iirc it has to do with copying / editing the OMAP object properties.
The good news, however, is that you can 'fake it' using File Layouts - http://docs.ceph.com/docs/mimic/cephfs/file-layouts/
In my case I was moving around / upgrading disks and wanted to change from unreplicated (well, r=1) to erasure coding (in my case, rs4.1). I was able to do this keeping the following in mind:
1. The original pool, cephfs_data, must remain as a replicated pool. I'm unsure why, IIRC some metadata can't be kept in erasure coded pools.
2. The metadata pool, cephfs_metadata, must also remain as a replicated pool.
3. Your new pool (the destination pool) can be created however you like.
4. This procedure involves rolling unavailability on a per-file basis.
This is from memory; I should do a better writeup elsewhere, but what I did was this:
1. Create your new pool. `ceph osd pool create
cephfs_data_ec_rs4.1
8 8 erasure rs4.1`
2. Set the xattr for the root directory to use the new pool: `setfattr -n ceph.file.layout.pool -v cephfs_data_ec_rs4.1 /cephfs_mountpoint/`
At this stage all new files will be written to the new pool. Unfortunately you can't change the layout of a file with data, so copying the files back into their own place is required. You can hack up a bash script to do this, or write a converter program. Here's the most relevant bit, per file, which copies the file first and then renames the new file to the old file:
func doConvert(filename string) error {
poolRewriteName, previousPoolName, err := newNearbyTempFiles(filename)
if err != nil {
return err
}
err = SetCephFSFileLayoutPool(poolRewriteName, []byte(*toPool))
if err != nil {
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
err = CopyFilePermissions(filename, poolRewriteName)
if err != nil {
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
//log.Printf("Copying %s to %s\n", filename, poolRewriteName)
err = CopyFile(filename, poolRewriteName)
if err != nil {
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
//log.Printf("Moving %s to %s\n", filename, previousPoolName)
err = MoveFile(filename, previousPoolName)
if err != nil {
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
//log.Printf("Moving %s to %s\n", poolRewriteName, filename)
err = MoveFile(poolRewriteName, filename)
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
poolRewriteName, previousPoolName, err := newNearbyTempFiles(filename)
if err != nil {
return err
}
err = SetCephFSFileLayoutPool(poolRewriteName, []byte(*toPool))
if err != nil {
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
err = CopyFilePermissions(filename, poolRewriteName)
if err != nil {
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
//log.Printf("Copying %s to %s\n", filename, poolRewriteName)
err = CopyFile(filename, poolRewriteName)
if err != nil {
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
//log.Printf("Moving %s to %s\n", filename, previousPoolName)
err = MoveFile(filename, previousPoolName)
if err != nil {
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
//log.Printf("Moving %s to %s\n", poolRewriteName, filename)
err = MoveFile(poolRewriteName, filename)
os.Remove(poolRewriteName)
os.Remove(previousPoolName)
return err
}
On Wed, May 15, 2019 at 10:31 AM Lars Täuber <taeuber@xxxxxxx> wrote:
Hi,
is there a way to migrate a cephfs to a new data pool like it is for rbd on nautilus?
https://ceph.com/geen-categorie/ceph-pool-migration/
Thanks
Lars
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