默认情况下, 创建top-level dev如果不指定扇区大小, 那么使用vdevs中最小的扇区大小作为zpool的扇区大小.
但是某些设备虽然是4K的扇区, 但是可能内核读到的扇区大小可能是512字节.
这样的话, 将对影响有比较大的影响, 所以在这种情况下, 创建zpool时可以指定扇区的大小. 添加top-devel时也可以指定扇区的大小, 尽量使用扇区大小一致的设备.
zpool创建完后不允许修改扇区的大小.
[root@db-172-16-3-150 man8]# zpool set ashift=9 zpp
cannot set property for 'zpp': property 'ashift' can only be set at creation timetop-level vdev的扇区大小指定.
[root@db-172-16-3-150 man8]# zpool create -o ashift=12 zpp mirror /ssd1/zfs.1 /ssd1/zfs.2
[root@db-172-16-3-150 man8]# zpool get all zpp|grep ashift
zpp ashift 12 local
[root@db-172-16-3-150 man8]# zpool get all zpp
NAME PROPERTY VALUE SOURCE
zpp size 95.5M -
zpp capacity 0% -
zpp altroot - default
zpp health ONLINE -
zpp guid 10118330420533444691 default
zpp version - default
zpp bootfs - default
zpp delegation on default
zpp autoreplace off default
zpp cachefile - default
zpp failmode wait default
zpp listsnapshots off default
zpp autoexpand off default
zpp dedupditto 0 default
zpp dedupratio 1.00x -
zpp free 94.9M -
zpp allocated 612K -
zpp readonly off -
zpp ashift 12 local
zpp comment - default
zpp expandsize 0 -
zpp freeing 0 default
zpp feature@async_destroy enabled local
zpp feature@empty_bpobj enabled local
zpp feature@lz4_compress enabled local添加top-level vdev时也可以指定.
[root@db-172-16-3-150 zpp]# zpool add -o ashift=10 zpp mirror /ssd1/zfs.5 /ssd1/zfs.6
[root@db-172-16-3-150 zpp]# dd if=/dev/zero of=./test1 bs=1k count=102400
102400+0 records in
102400+0 records out
104857600 bytes (105 MB) copied, 2.75559 s, 38.1 MB/s
[root@db-172-16-3-150 zpp]# zpool list -v zpp
NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT
zpp 286M 204M 82.8M 71% 1.00x ONLINE -
mirror 95.5M 78.3M 17.2M -
/ssd1/zfs.1 - - - -
/ssd1/zfs.2 - - - -
mirror 95.5M 81.1M 14.4M -
/ssd1/zfs.3 - - - -
/ssd1/zfs.4 - - - -
mirror 95.5M 44.3M 51.2M -
/ssd1/zfs.5 - - - -
/ssd1/zfs.6 - - - -[参考]
1. man zpool
The following property can be set at creation time:
ashift
Pool sector size exponent, to the power of 2 (internally referred to as "ashift"). I/O operations will be
aligned to the specified size boundaries. Additionally, the minimum (disk) write size will be set to the
specified size, so this represents a space vs. performance trade-off. The typical case for setting this
property is when performance is important and the underlying disks use 4KiB sectors but report 512B sectors
to the OS (for compatibility reasons); in that case, set ashift=12 (which is 1<<12 = 4096).
For optimal performance, the pool sector size should be greater than or equal to the sector size of the
underlying disks. Since the property cannot be changed after pool creation, if in a given pool, you ever
want to use drives that report 4KiB sectors, you must set ashift=12 at pool creation time.2. 其他属性
Properties
Each pool has several properties associated with it. Some properties are read-only statistics while others are
configurable and change the behavior of the pool. The following are read-only properties:
available Amount of storage available within the pool. This property can also be referred to by its
shortened column name, "avail".
capacity Percentage of pool space used. This property can also be referred to by its shortened col-
umn name, "cap".
expandsize Amount of uninitialized space within the pool or device that can be used to increase the
total capacity of the pool. Uninitialized space consists of any space on an EFI labeled
vdev which has not been brought online (i.e. zpool online -e). This space occurs when a
LUN is dynamically expanded.
free The amount of free space available in the pool.
freeing After a file system or snapshot is destroyed, the space it was using is returned to the
pool asynchronously. freeing is the amount of space remaining to be reclaimed. Over time
freeing will decrease while free increases.
health The current health of the pool. Health can be "ONLINE", "DEGRADED", "FAULTED", " OFFLINE",
"REMOVED", or "UNAVAIL".
guid A unique identifier for the pool.
size Total size of the storage pool.
unsupported@feature_Information about unsupported features that are enabled on the pool. See zpool-features(5)
for details.
used Amount of storage space used within the pool.
The space usage properties report actual physical space available to the storage pool. The physical space can
be different from the total amount of space that any contained datasets can actually use. The amount of space
used in a raidz configuration depends on the characteristics of the data being written. In addition, ZFS
reserves some space for internal accounting that the zfs(8) command takes into account, but the zpool command
does not. For non-full pools of a reasonable size, these effects should be invisible. For small pools, or pools
that are close to being completely full, these discrepancies may become more noticeable.
The following property can be set at creation time:
ashift
Pool sector size exponent, to the power of 2 (internally referred to as "ashift"). I/O operations will be
aligned to the specified size boundaries. Additionally, the minimum (disk) write size will be set to the
specified size, so this represents a space vs. performance trade-off. The typical case for setting this
property is when performance is important and the underlying disks use 4KiB sectors but report 512B sectors
to the OS (for compatibility reasons); in that case, set ashift=12 (which is 1<<12 = 4096).
For optimal performance, the pool sector size should be greater than or equal to the sector size of the
underlying disks. Since the property cannot be changed after pool creation, if in a given pool, you ever
want to use drives that report 4KiB sectors, you must set ashift=12 at pool creation time.
The following property can be set at creation time and import time:
altroot
Alternate root directory. If set, this directory is prepended to any mount points within the pool. This can
be used when examining an unknown pool where the mount points cannot be trusted, or in an alternate boot
environment, where the typical paths are not valid. altroot is not a persistent property. It is valid only
while the system is up. Setting altroot defaults to using cachefile=none, though this may be overridden
using an explicit setting.
The following properties can be set at creation time and import time, and later changed with the zpool set com-
mand:
autoexpand=on | off
Controls automatic pool expansion when the underlying LUN is grown. If set to on, the pool will be resized
according to the size of the expanded device. If the device is part of a mirror or raidz then all devices
within that mirror/raidz group must be expanded before the new space is made available to the pool. The
default behavior is off. This property can also be referred to by its shortened column name, expand.
autoreplace=on | off
Controls automatic device replacement. If set to "off", device replacement must be initiated by the admin-
istrator by using the "zpool replace" command. If set to "on", any new device, found in the same physical
location as a device that previously belonged to the pool, is automatically formatted and replaced. The
default behavior is "off". This property can also be referred to by its shortened column name, "replace".
bootfs=pool/dataset
Identifies the default bootable dataset for the root pool. This property is expected to be set mainly by
the installation and upgrade programs.
cachefile=path | none
Controls the location of where the pool configuration is cached. Discovering all pools on system startup
requires a cached copy of the configuration data that is stored on the root file system. All pools in this
cache are automatically imported when the system boots. Some environments, such as install and clustering,
need to cache this information in a different location so that pools are not automatically imported. Set-
ting this property caches the pool configuration in a different location that can later be imported with
"zpool import -c". Setting it to the special value "none" creates a temporary pool that is never cached,
and the special value ’’ (empty string) uses the default location.
Multiple pools can share the same cache file. Because the kernel destroys and recreates this file when
pools are added and removed, care should be taken when attempting to access this file. When the last pool
using a cachefile is exported or destroyed, the file is removed.
comment=text
A text string consisting of printable ASCII characters that will be stored such that it is available even
if the pool becomes faulted. An administrator can provide additional information about a pool using this
property.
delegation=on | off
Controls whether a non-privileged user is granted access based on the dataset permissions defined on the
dataset. See zfs(8) for more information on ZFS delegated administration.
failmode=wait | continue | panic
Controls the system behavior in the event of catastrophic pool failure. This condition is typically a
result of a loss of connectivity to the underlying storage device(s) or a failure of all devices within the
pool. The behavior of such an event is determined as follows:
wait Blocks all I/O access until the device connectivity is recovered and the errors are cleared.
This is the default behavior.
continue Returns EIO to any new write I/O requests but allows reads to any of the remaining healthy
devices. Any write requests that have yet to be committed to disk would be blocked.
panic Prints out a message to the console and generates a system crash dump.
feature@feature_name=enabled
The value of this property is the current state of feature_name. The only valid value when setting this
property is enabled which moves feature_name to the enabled state. See zpool-features(5) for details on
feature states.
listsnaps=on | off
Controls whether information about snapshots associated with this pool is output when "zfs list" is run
without the -t option. The default value is "off".
version=version
The current on-disk version of the pool. This can be increased, but never decreased. The preferred method
of updating pools is with the "zpool upgrade" command, though this property can be used when a specific
version is needed for backwards compatibility. Once feature flags are enabled on a pool this property will
no longer have a value.时间： 2024-10-30 07:03:54