Some disks with internal sectors larger than 512 bytes (e.g., 4k) can
suffer from bad write performance when ashift is not configured
correctly. This is caused by the disk not reporting its actual sector
size, but a sector size of 512 bytes. The drive may behave this way
for compatibility reasons. For example, the WDC WD20EARS disks are
known to exhibit this behavior.
When creating a zpool, ZFS takes that wrong sector size and sets the
"ashift" property accordingly (to 9: 1<<9=512), whereas it should be
set to 12 for 4k sectors (1<<12=4096).
This patch allows an adminstrator to manual specify the known correct
ashift size at 'zpool create' time. This can significantly improve
performance in certain cases. However, it will have an impact on your
total pool capacity. See the updated ashift property description
in the zpool.8 man page for additional details.
Valid values for the ashift property range from 9 to 17 (512B-128KB).
Additionally, you may set the ashift to 0 if you wish to auto-detect
the sector size based on what the disk reports, this is the default
behavior. The most common ashift values are 9 and 12.
Example:
zpool create -o ashift=12 tank raidz2 sda sdb sdc sdd
Closes#280
Original-patch-by: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit fixes issue on
https://github.com/behlendorf/zfs/issues/#issue/172
Changes:
- update BLKZNAME to use _IOR instead of _IO. Kernel 2.6.32 allows
read parameters (copy_to_user) with _IO, while newer kernels (tested
Archlinux's 2.6.37 kernel) enforces _IOR (which is correct)
- fix return code and message on error
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit allows zvols with names longer than 32 characters, which
fixes issue on https://github.com/behlendorf/zfs/issues/#issue/102.
Changes include:
- use /dev/zd* device names for zvol, where * is the device minor
(include/sys/fs/zfs.h, module/zfs/zvol.c).
- add BLKZNAME ioctl to get dataset name from userland
(include/sys/fs/zfs.h, module/zfs/zvol.c, cmd/zvol_id).
- add udev rule to create /dev/zvol/[dataset_name] and the legacy
/dev/[dataset_name] symlink. For partitions on zvol, it will create
/dev/zvol/[dataset_name]-part* (etc/udev/rules.d/60-zvol.rules,
cmd/zvol_id).
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
One of the neat tricks an autoconf style project is capable of
is allow configurion/building in a directory other than the
source directory. The major advantage to this is that you can
build the project various different ways while making changes
in a single source tree.
For example, this project is designed to work on various different
Linux distributions each of which work slightly differently. This
means that changes need to verified on each of those supported
distributions perferably before the change is committed to the
public git repo.
Using nfs and custom build directories makes this much easier.
I now have a single source tree in nfs mounted on several different
systems each running a supported distribution. When I make a
change to the source base I suspect may break things I can
concurrently build from the same source on all the systems each
in their own subdirectory.
wget -c http://github.com/downloads/behlendorf/zfs/zfs-x.y.z.tar.gz
tar -xzf zfs-x.y.z.tar.gz
cd zfs-x-y-z
------------------------- run concurrently ----------------------
<ubuntu system> <fedora system> <debian system> <rhel6 system>
mkdir ubuntu mkdir fedora mkdir debian mkdir rhel6
cd ubuntu cd fedora cd debian cd rhel6
../configure ../configure ../configure ../configure
make make make make
make check make check make check make check
This change also moves many of the include headers from individual
incude/sys directories under the modules directory in to a single
top level include directory. This has the advantage of making
the build rules cleaner and logically it makes a bit more sense.
Christian Kohlschütter
Fajar A. Nugraha
Brian Behlendorf