Hello list, while we used adaptec controller with battery cache for years we recently switched to dell hw using the perc controllers which are rebranded lsi/broadcom controllers. We're running btrfs subvolume / snapshot workloads and while those are very fast on btrfs using a btrfs raid 0 on top of several raid 5 running on adaptec (battery backed up) in write back mode. The performance really sucks on those LSI controllers even the one i have has 8GB cache instead of just 1GB at adaptec. Especially sync / fsync are awfully slow taking sometimes 30-45 minutes while btrfs is doing snapshots. The workload on all machines is the same and the disks are ok. Is there a way to disable FLUSH / sync at all for those devices? Just to test? I'm already using nobarrier mount option on btrfs but this does not help either. Thanks! Greets, Stefan
