106 lines
4.4 KiB
HTML
106 lines
4.4 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE> Linux DPT Hardware RAID HOWTO : Usage</TITLE>
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<LINK HREF="DPT-Hardware-RAID-HOWTO-6.html" REL=next>
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<LINK HREF="DPT-Hardware-RAID-HOWTO-4.html" REL=previous>
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<LINK HREF="DPT-Hardware-RAID-HOWTO.html#toc5" REL=contents>
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</HEAD>
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<BODY>
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<A HREF="DPT-Hardware-RAID-HOWTO-6.html">Next</A>
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<A HREF="DPT-Hardware-RAID-HOWTO-4.html">Previous</A>
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<A HREF="DPT-Hardware-RAID-HOWTO.html#toc5">Contents</A>
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<HR>
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<H2><A NAME="s5">5. Usage</A></H2>
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<H2><A NAME="ss5.1">5.1 fdisk, mke2fs, mount, etc.</A>
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</H2>
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<P> You can now start treating the RAID as a regular disk. The first
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thing you'll need to do is partition the disk (using fdisk). You'll
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then need to set up an ext2 filesystem. This can be done
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by running the command:
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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% mkfs -t ext2 /dev/sdxN
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</PRE>
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</CODE></BLOCKQUOTE>
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<P>where /dev/sdxN is the name of the SCSI partition. Once you do this,
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you'll be able to mount the partitions and use them as you would any
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other disk (including adding entries in /etc/fstab).
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<H2><A NAME="ss5.2">5.2 Hot swapping </A>
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</H2>
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<P> We first tried to test hot swapping by removing a drive and putting
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it back in the DPT-supplied enclosure/tower (which you buy for an
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additional cost). Before we could carry this out to completion, one
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of the disks failed (as I write this, the beeping is driving me
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crazy). Even though one of the disks failed, all the data on the RAID
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drive was accessible.
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<P> Instead of replacing the drive, we just went through the motions
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of hot swapping and put the same drive back in. The drive rebuilt
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itself and everything turned out okay. During the time the disk had
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filed, and during the rebuilding process, all the data was
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accessible. Though it should be noted that if another disk had failed,
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we'd have been in serious trouble.
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<H2><A NAME="ss5.3">5.3 Performance </A>
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</H2>
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<P> Here's the output of the Bonnie program, on a 2144 UW with 9x3=17
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GB RAID 5 setup, using the EATA DMA driver. The RAID is on a dual
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processor Pentium Pro machine running Linux 2.0.33. For comparison,
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the Bonnie results for the IDE drive on that machine are also given.
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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-------Sequential Output-------- ---Sequential Input-- --Random--
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-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
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MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
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RAID 100 9210 96.8 1613 5.9 717 5.8 3797 36.1 90931 96.8 4648.2 159.2
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IDE 100 3277 32.0 6325 23.5 2627 18.3 4818 44.8 59697 88.0 575.9 16.3
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</PRE>
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</CODE></BLOCKQUOTE>
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<P> Some people have disputed the above timings (and rightly so---I've
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been unable to try it out on our machines since they're completely loaded)
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because the size of the file used may have led to it being cached
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(resulting in an unusually good performance report). Here are some
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timings with a 3344 UW controller:
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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-------Sequential Output-------- ---Sequential Input-- --Random--
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-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
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MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
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1000 1714 17.2 1689 6.0 1200 5.7 5263 40.2 7023 12.1 51.3 2.2
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</PRE>
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</CODE></BLOCKQUOTE>
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<P>And here are some timings on a SCSI-to-SCSI RAID system:
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<P>
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<BLOCKQUOTE><CODE>
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<PRE>
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-------Sequential Output-------- ---Sequential Input-- --Random--
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-Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
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MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
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64 7465 100.0 70287 98.7 37012 97.7 8074 99.2 *****100.3 ***** 196.6
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128 7289 99.3 67595 98.5 35294 98.6 7792 97.6 *****100.3 ***** 195.8
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256 7222 98.8 44844 69.6 16096 51.8 5787 72.7 ***** 99.8 ***** 85.2
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512 7138 98.4 13871 23.2 7888 29.3 7183 89.3 16488 27.2 1585. 11.5
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1024 6908 95.8 12270 21.5 7161 25.4 7373 90.4 16527 28.2 123.8 1.8
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2047 6081 84.1 12664 22.6 7191 25.6 7289 89.5 16573 28.5 75.0 1.2
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***** results exceed column width (> 100 MB/sec, > 10000 seeks/sec)
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host: Dual PII 400 MHz, 2 x U2W, 512 MB RAM, no internal disks
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RAID: IFT 3102 UA 128 MB Cache, RAID-5, 6 x 9 GB
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OS: SuSE Linux 6.0 with Kernel 2.2.3
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</PRE>
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</CODE></BLOCKQUOTE>
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<HR>
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<A HREF="DPT-Hardware-RAID-HOWTO-6.html">Next</A>
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<A HREF="DPT-Hardware-RAID-HOWTO-4.html">Previous</A>
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<A HREF="DPT-Hardware-RAID-HOWTO.html#toc5">Contents</A>
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</BODY>
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</HTML>
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