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IBM Systems Group
April 2005
AIX AK April 2005
Forschungszentrum Karlsruhe
AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group IBM Storage with Linux 2005 Alexander Warmuth ATS EMEA Storage AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group Topics What is supported The Linux SCSI subsystem Linux Kernel version 2.6 Multipathing scenarios Tape specifics AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group What Is Supported What is supported The Linux SCSI subsystem Linux Kernel version 2.6 Multipathing scenarios Tape specifics AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group IBM Storage Support for Linux Enterprise Storage Server DS4000 Storage Servers Linear Tape Open Network Attached Storage Enterprise Tape Storage Virtualization AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group pLinux Support Disk ESS: SLES8, SLES9, RH-EL 3 SDD available JS20, p5 and OP: SLES9, RH-EL 3 Remote boot supported DS6000, DS8000: SLES8, SLES9, RH-EL 3 SDD available JS20: SLES8, SLES9, RH-EL 3 p5 and OP: RH-EL 3 only Remote boot supported DS4000: SLES8, SLES9, RH-EL 3 Emulex Multipulse driver for multipathing SLES 9 single path only Remote boot with JS20, others require RPQ AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group pLinux Support Tape LTO: SLES 8, SLES 9, RH-EL 3 Data Path (for 3584) and Media Changer failover supported 359x: SLES 8, SLES 9, RH-EL 3 Data path failover supported for 3592 Parallel SCSI attachment also supported Advanced IBMtape device driver IBMtapeutil AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group The Linux SCSI Subsystem What is supported The Linux SCSI subsystem Linux Kernel version 2.6 Multipathing scenarios Tape specifics AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group Linux Device Addressing Everything is a file! brw-rw---- 1 root disk 8, 0 2003-03-14 14:07 /dev/sda brw-rw---- 1 root disk 8, 1 2003-03-14 14:07 /dev/sda1 brw-rw---- 1 root disk 3, 0 2003-03-14 14:07 /dev/hda crw-rw---- 1 root disk 9, 0 2003-03-14 14:07 /dev/st0 crw-rw---- 1 root disk 9, 96 2003-03-14 14:07 /dev/st0a crw-rw---- 1 root disk 9, 32 2003-03-14 14:07 /dev/st0l crw-rw---- 1 roo
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IBM Systems Group Design User Space Kernel Space SD SR ST SG IBMTape disks cdrom/dvd tapes upper level pass-through char device block device block device char device char device (IBMtape.o) (sd_mod.o) (sr_mod.o) (st.o) (sg.o) SCSI unifying layer mid level (scsi_mod.o, scsi*.[hc], hosts.[hc], constants.c) SCSI / FC Host Bus Pseudo drivers for lower level Adapter drivers non SCSI buses (e.g. qla2300.o) (e.g. ide-scsi.o) SCSI / FC SCSI / FC SCSI / FC Parallel SCSI / SAN SCSI / FC disks disks di
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IBM Systems Group Linux Kernel Version 2.6 What is supported The Linux SCSI subsystem Linux Kernel version 2.6 Multipathing scenarios Tape specifics AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group Storage Changes in Linux Kernel 2.6 Increased number of SCSI devices Persistent device names Improved hotplugging Native multipathing LVM 2 Improved I/O performance Larger devices and filesystems AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group Wellknown Linux SCSI Limitations Limited number of devices Fixed with Kernel Up to 256 SCSI disk devices 2.6 Up to 256 SCSI generic devices Up to 32 tape drives Still there Gaps in LUN sequence Fixed with Kernel Limited “on-the-fly” attachment 2.6 Conditionally Device re-ordering fixed with Kernel 2.6 AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group Other Problems and Pitfalls Multiple LUN support of RH-EL DS4000 Specific QLogic failover driver configuration Potential LUN thrashing UTM (Access LUN) ESS, DS6000, DS8000 Specific SDD and LVM, ext3 Mounting PPRC targets DS6000 Preferred Path AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group Large filesystems support Linux Kernel Limits Max file size: 2 TB (2^41 bytes) Max file system size: 8 ZB (2^73 bytes) AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group Multipathing Scenarios What is supported The Linux SCSI subsystem Linux Kernel version 2.6 Multipathing scenarios Tape specifics AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group Multipathing Concepts Linux host 1 Linux host 2 HBA 0 HBA 1 HBA 0 HBA 1 Linux host 1 Linux host 2 HBA 0 HBA 1 HBA 0 HBA 1 1 2 DS8000 Linux host 1 Linux host 2 Disk HBA 0 HBA 1 HBA 0 HBA 1 LUN 0 1 2 DS6000 Disk A DS4000 B LUN 0 Disk LUN 0 AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group LUN Transfer to Alternate Controller DS4000 transfers LUNs to alternate controller Volumes are owned by one controller Volumes can be accessed through both controllers Volume ownership is always transferred to the controller that is used for volume access -> transfer time approx 1 s Two multipathing solutions available QLogic failover driver uses AVT Difficult to configure Potential LUN thrashing RDAC uses inband communication Self configuring Suitable fo
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IBM Systems Group LUN Thrashing Scenario Linux host 1 Linux host 2 HBA 0 HBA 1 HBA 0 HBA 1 A B DS4000 Disk LUN 0 AIX-AK FZK 2005 © 2005 IBM Corporation
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IBM Systems Group LUN Thrashing Scenario Linux host 1 Linux host 2 HBA 0 HBA 1 HBA 0 HBA 1 A B DS4000 Disk LUN 0 AIX-AK FZK 2005 © 2005 IBM Corporation
