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(itstool) path: listitem/para
(itstool) id: book.translate.xml#zfs-advanced-tuning-arc_meta_limit
<emphasis><varname>vfs.zfs.arc_meta_limit</varname></emphasis> - Limit the portion of the <link linkend="zfs-term-arc"><acronym>ARC</acronym></link> that can be used to store metadata. The default is one fourth of <varname>vfs.zfs.arc_max</varname>. Increasing this value will improve performance if the workload involves operations on a large number of files and directories, or frequent metadata operations, at the cost of less file data fitting in the <link linkend="zfs-term-arc"><acronym>ARC</acronym></link>. This value can be adjusted at runtime with <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry> and can be set in <filename>/boot/loader.conf</filename> or <filename>/etc/sysctl.conf</filename>.
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Context English Chinese (Simplified) (zh_CN) State
Delegating Permission Delegation
委托权限委托
<command>zfs allow <replaceable>someuser</replaceable> allow <replaceable>mydataset</replaceable></command> gives the specified user the ability to assign any permission they have on the target dataset, or its children, to other users. If a user has the <literal>snapshot</literal> permission and the <literal>allow</literal> permission, that user can then grant the <literal>snapshot</literal> permission to other users.
<command>zfs allow <replaceable>someuser</replaceable> allow <replaceable>mydataset</replaceable></command> 可以给予指定的使用者有权限指派它们在目标数据集或其子数据集上拥有的任何权限给其他人。若该使用者拥有 <literal>snapshot</literal> 权限及 <literal>allow</literal> 权限,则该使用者可以授权 <literal>snapshot</literal> 权限给其他使用者。
Tuning
优化调整
There are a number of tunables that can be adjusted to make <acronym>ZFS</acronym> perform best for different workloads.
这里有数个可调校的项目可以调整,来让 <acronym>ZFS</acronym> 在面对各种工作都能以最佳状况运作。
<emphasis><varname>vfs.zfs.arc_max</varname></emphasis> - Maximum size of the <link linkend="zfs-term-arc"><acronym>ARC</acronym></link>. The default is all <acronym>RAM</acronym> but 1 GB, or 5/8 of all <acronym>RAM</acronym>, whichever is more. However, a lower value should be used if the system will be running any other daemons or processes that may require memory. This value can be adjusted at runtime with <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry> and can be set in <filename>/boot/loader.conf</filename> or <filename>/etc/sysctl.conf</filename>.
<emphasis><varname>vfs.zfs.arc_max</varname></emphasis> - <link linkend="zfs-term-arc"><acronym>ARC</acronym></link>最大容量。默认为全部RAM。如果有运行其他程序,此处应设置一个较低的值可在系统运行时使用<citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>调整,也可在 <filename>/boot/loader.conf</filename> 或 <filename>/etc/sysctl.conf</filename>中进行设置(需重启系统)。
<emphasis><varname>vfs.zfs.arc_meta_limit</varname></emphasis> - Limit the portion of the <link linkend="zfs-term-arc"><acronym>ARC</acronym></link> that can be used to store metadata. The default is one fourth of <varname>vfs.zfs.arc_max</varname>. Increasing this value will improve performance if the workload involves operations on a large number of files and directories, or frequent metadata operations, at the cost of less file data fitting in the <link linkend="zfs-term-arc"><acronym>ARC</acronym></link>. This value can be adjusted at runtime with <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry> and can be set in <filename>/boot/loader.conf</filename> or <filename>/etc/sysctl.conf</filename>.
 
<emphasis><varname>vfs.zfs.arc_min</varname></emphasis> - Minimum size of the <link linkend="zfs-term-arc"><acronym>ARC</acronym></link>. The default is one half of <varname>vfs.zfs.arc_meta_limit</varname>. Adjust this value to prevent other applications from pressuring out the entire <link linkend="zfs-term-arc"><acronym>ARC</acronym></link>. This value can be adjusted at runtime with <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry> and can be set in <filename>/boot/loader.conf</filename> or <filename>/etc/sysctl.conf</filename>.
 
<emphasis><varname>vfs.zfs.vdev.cache.size</varname></emphasis> - A preallocated amount of memory reserved as a cache for each device in the pool. The total amount of memory used will be this value multiplied by the number of devices. This value can only be adjusted at boot time, and is set in <filename>/boot/loader.conf</filename>.
<emphasis><varname>vfs.zfs.vdev.cache.size</varname></emphasis> - 预先分配的内存量,作为池中每个设备的缓存。使用的内存总量将是这个值乘以设备数量。此值只能在操作系统启动时调整,可以在 <filename>/boot/loader.conf</filename>中设置。
<emphasis><varname>vfs.zfs.min_auto_ashift</varname></emphasis> - Minimum <varname>ashift</varname> (sector size) that will be used automatically at pool creation time. The value is a power of two. The default value of <literal>9</literal> represents <literal>2^9 = 512</literal>, a sector size of 512 bytes. To avoid <emphasis>write amplification</emphasis> and get the best performance, set this value to the largest sector size used by a device in the pool.
<emphasis><varname>vfs.zfs.min_auto_ashift</varname></emphasis> - 在创建池时自动使用的最小<varname>ashift</varname>(扇区大小)。该值是二的幂。默认值<literal>9</literal>表示<literal>2^9 = 512</literal>,扇区大小为512字节。为了避免<emphasis>写放大</emphasis>并获得最佳性能,请将此值设置为池中设备使用的最大扇区大小。
Many drives have 4 KB sectors. Using the default <varname>ashift</varname> of <literal>9</literal> with these drives results in write amplification on these devices. Data that could be contained in a single 4 KB write must instead be written in eight 512-byte writes. <acronym>ZFS</acronym> tries to read the native sector size from all devices when creating a pool, but many drives with 4 KB sectors report that their sectors are 512 bytes for compatibility. Setting <varname>vfs.zfs.min_auto_ashift</varname> to <literal>12</literal> (<literal>2^12 = 4096</literal>) before creating a pool forces <acronym>ZFS</acronym> to use 4 KB blocks for best performance on these drives.
许多驱动器有4KB的扇区。在这些硬盘上使用默认的<varname>ashift</varname><literal>9</literal>,会导致这些设备上的写入量放大。原本可以包含在单个 4 KB 写入中的数据必须以 8 个 512 字节的写入方式写入。<acronym>ZFS</acronym>在创建池时,会尝试从所有设备中读取本机扇区大小,但许多具有4 KB扇区的驱动器报告说,为了兼容性,它们的扇区是512字节。在创建池之前,将 <varname>vfs.zfs.min_auto_ashift</varname>设置为 <literal>12</literal> (<literal>2^12 = 4096</literal>),可迫使 <acronym>ZFS</acronym>使用 4 KB 块,以获得这些驱动器上的最佳性能。
Forcing 4 KB blocks is also useful on pools where disk upgrades are planned. Future disks are likely to use 4 KB sectors, and <varname>ashift</varname> values cannot be changed after a pool is created.
强制使用 4KB 块在计划进行磁盘升级的池中也很有用。将来的磁盘可能会使用 4 KB 扇区,并且在创建池后无法更改<varname>ashift</varname>值。

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(itstool) id: book.translate.xml#zfs-advanced-tuning-arc_meta_limit
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books/zh_CN/handbook.po, string 6652