RHEL6의 EXT4 파일시스템에서 SSD 트림 활성화 방법

<DIV> <P> </P> <P>레드햇에서 SSD 사용하시는 분들은 트림지원이 관건이 될거 같네요.</P> <P>EXT4파일시스템에서만 옵션을 통해서 할수 있다고 하는데</P> <P>다른 RHEL5의 EXT3에서는 방법이 없을까요..</P> <P></P> <P> </P> <P><A href="http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/newmds-ssdtuning.html">http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/newmds-ssdtuning.html</A></P> <P> </P> <P>설정을 위해서는 아래 내용을 참조바랍니다:</P> <P> </P> <P>/etc/fstab에 아래와 같이 discard 옵션을 넣어주면 됩니다. ext4만 지원합니다.</P> <P> </P> <P>/dev/sda5  /opt  ext4  defaults,<STRONG>discard</STRONG>  0 0</P> <P> </P> <P> </P> <DIV class=titlepage> <DIV> <DIV> <H2 id=ssddeploy class=title>Deployment Considerations</H2></DIV></DIV></DIV><A id=id3208468 class=indexterm></A><A id=id3208480 class=indexterm></A> <DIV class=para>Because of the internal layout and operation of SSDs, it is best to partition devices on an internal <EM class=firstterm>erase block boundary</EM>. Partitioning utilities in Red Hat Enterprise Linux 6 chooses sane defaults if the SSD exports topology information. This is especially true if the exported topology information includes alignment offsets and optimal I/O sizes. </DIV> <DIV class=para>However, if the device <SPAN class=emphasis><EM>does not</EM></SPAN> export topology information, Red Hat recommends that the first partition be created at a 1MB boundary. </DIV> <DIV class=para>In addition, keep in mind that logical volumes, device-mapper targets, and <CODE class=command><FONT face=GulimChe>md</FONT></CODE> targets do not support <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE>. As such, the default Red Hat Enterprise Linux 6 installation will not allow the use of the <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE> command, since this install uses DM-linear targets. </DIV> <DIV class=para>Red Hat also warns that software RAID levels 1, 4, 5, and 6 are not recommended for use on SSDs. During the initialization stage of these RAID levels, some RAID management utilities (such as <CODE class=command><FONT face=GulimChe>mdadm</FONT></CODE>) write to <SPAN class=emphasis><EM>all</EM></SPAN> of the blocks on the storage device to ensure that checksums operate properly. This will cause the performance of the SSD to degrade quickly. </DIV> <DIV class=para>At present, ext4 is the only fully-supported file system that supports <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE>. To enable <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE> commands on a device, use the <CODE class=command><FONT face=GulimChe>mount</FONT></CODE> option <CODE class=command><FONT face=GulimChe>discard</FONT></CODE>. For example, to mount <CODE class=filename><FONT face=GulimChe>/dev/sda2</FONT></CODE> to <CODE class=filename><FONT face=GulimChe>/mnt</FONT></CODE> with <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE> enabled, run: </DIV> <DIV class=para><STRONG><CODE class=command><FONT face=GulimChe>mount -t ext4 -o discard /dev/sda2 /mnt</FONT></CODE> </STRONG></DIV> <DIV class=para>By default, ext4 does not issue the <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE> command. This is mostly to avoid problems on devices which may not properly implement the <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE> command. The Linux <CODE class=command><FONT face=GulimChe>swap</FONT></CODE> code will issue <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE> commands to <CODE class=command><FONT face=GulimChe>TRIM</FONT></CODE>-enabled devices, and there is no option to control this behaviour </DIV></DIV>