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| '''This is a WIP'''
| | #REDIRECT [[Linux iSCSI Target (TCM)]] |
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| == Introduction ==
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| This HOW-TO is focusing on performance. This is why I made some decisions targeted on performance instead of security (like you are used in Alpine Linux).
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| This means we are not using grsec and not using a firewall. I presume you will take security actions on another level.
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| To get started, you can download a boot cd here:
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| http://alpine.nethq.org/distfiles/alpine-scst-110105-x86.iso
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| == Content ==
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| * Vanilla Kernel with SCST patches (linux-scst)
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| * SCST modules and SCST ISCSI modules (linux-scst)
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| * Linux software raid and raid level (mdadm)
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| * Volume Management (LVM2)
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| * SCST administration (scstadmin)
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| * Linux raid monitoring
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| == Linux software raid ==
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| In my personal setup i have 4 pieces of WD RE4 1TB drives which i want to use in the best performance raid level with redundancy.
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| According to many mailing lists and opinion of the Linux raid author RAID10 with layout f2 (far) seems to preform best while still having redundancy.
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| Please remember with RAID10 50% of your hard disk space will go to redundancy, but performance is almost the same as RAID0 (stripe).
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| For most up-to-date information regarding Linux software raid: https://raid.wiki.kernel.org/index.php/Overview
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| RAID10 has multiple layout types. f(far)2 in tests seem to preform the best. Please see above link for references.
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| mdadm -v --create /dev/md0 --level=raid10 --layout=f2 --raid-devices=4 /dev/sda /dev/sdb /dev/sdc /dev/sdd
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| I am not using partitions on my disks, although there are reasons to use partitions, see here:
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| https://raid.wiki.kernel.org/index.php/Partition_Types
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| You can now monitor your raid (re)building: cat /proc/mdstat
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| By default, the rebuild speed will be set and can be checked and changed here:
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| cat /proc/sys/dev/raid/speed_limit_max
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| cat /proc/sys/dev/raid/speed_limit_min
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| make sure we have raid10 module loaded at boot
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| echo raid10 >> /etc/modules
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| When you are happy with your raid configuration, save its information to mdamd.conf file
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| mdadm --detail --scan >> /etc/mdadm.conf
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| It should display something like
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| ARRAY /dev/md0 metadata=1.2 name=scst:0 UUID=71fc93b8:3fef0057:9f5feec1:7d9e57e8
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| == Monitor software raid ==
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| Linux software raid can be monitored with mdadm daemon option. Alpine Linux includes an initd script which can invoke the daemon
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| /etc/init.d/mdadm
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| It will be default monitor the array's defined in mdadm.conf. To receive email notifications about array issues, we need to provide our email address inside mdadm.conf:
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| MAILADDR me@inter.net
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| Because mdadm cannot send email itself, we need to setup an sendmail (replacement) program.
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| apk add ssmtp
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| Ssmtp can be configured by editing /etc/ssmtp/ssmtp.conf
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| You can monitor messages (syslog) for actions invoked by mmdadm.
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| If you have your own monitoring system active, you can also let mdadm issue a script and notify it.
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| == SCST and iSCSI management ==
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| To add an device
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| scstadmin -open_dev disk01 -handler vdisk_fileio -attributes filename=/mnt/array1/disk01,nv_cache=1
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| To close a device
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| scstadmin -close_dev disk01 -handler vdisk_fileio
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