these are the zfs settings I use on my MDSes
zfs set mountpoint=none mdt0
zfs set sync=disabled mdt0
zfs set atime=off amdt0
zfs set redundant_metadata=most mdt0
zfs set xattr=sa mdt0
if youor MDT partition is on a 4KB sector disk then you can use
ashift=12 when you create the filesystem but zfs is pretty smart and in
my case it recognized it automatically and used ashift=12 automatically.
also here are the zfs kernel modules parameters i use to ahve better
performance. I use it on both MDS and OSSes
options zfs zfs_prefetch_disable=1
options zfs zfs_txg_history=120
options zfs metaslab_debug_unload=1
#
options zfs zfs_vdev_scheduler=deadline
options zfs zfs_vdev_async_write_active_min_dirty_percent=20
#
options zfs zfs_vdev_scrub_min_active=48
options zfs zfs_vdev_scrub_max_active=128
#options zfs zfs_vdev_sync_write_min_active=64
#options zfs zfs_vdev_sync_write_max_active=128
#
options zfs zfs_vdev_sync_write_min_active=8
options zfs zfs_vdev_sync_write_max_active=32
options zfs zfs_vdev_sync_read_min_active=8
options zfs zfs_vdev_sync_read_max_active=32
options zfs zfs_vdev_async_read_min_active=8
options zfs zfs_vdev_async_read_max_active=32
options zfs zfs_top_maxinflight=320
options zfs zfs_txg_timeout=30
options zfs zfs_dirty_data_max_percent=40
options zfs zfs_vdev_async_write_min_active=8
options zfs zfs_vdev_async_write_max_active=32
some people may disagree with me anyway after years of trying different
options I reached this stable configuration.
then there are a bunch of other important Lustre level optimizations
that you can do if you are looking for performance increase.
Cheers
Rick
On 3/13/19 11:44 AM, Kurt Strosahl wrote:
Good Afternoon,
I'm reviewing the zfs parameters for a new metadata system and I
was looking to see if anyone had examples (good or bad) of zfs
parameters? I'm assuming that the MDT won't benefit from a recordsize
of 1MB, and I've already set the ashift to 12. I'm using an MDT/MGS
made up of a stripe across mirrored ssds.
w/r,
Kurt
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