High performance SCST iSCSI Target on Linux software Raid: Difference between revisions
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This is a WIP | '''This is a WIP''' | ||
== Introduction == | == 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). | 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). | ||
This means we are not using grsec and not using a firewall. I presume you will take security actions on another level. | This means we are not using grsec and not using a firewall. I presume you will take security actions on another level. | ||
To get started, you can download a boot cd here: | |||
http://alpine.nethq.org/distfiles/alpine-scst-110105-x86.iso | |||
== Content == | == Content == | ||
Revision as of 09:26, 5 January 2011
This is a WIP
Introduction
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). This means we are not using grsec and not using a firewall. I presume you will take security actions on another level.
To get started, you can download a boot cd here:
http://alpine.nethq.org/distfiles/alpine-scst-110105-x86.iso
Content
- Vanilla Kernel with SCST patches (linux-scst)
- SCST modules and SCST ISCSI modules (linux-scst)
- Linux software raid and raid level (mdadm)
- Volume Management (LVM2)
- SCST administration (scstadmin)
- Linux raid monitoring
Linux software raid
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. According to many mailing lists and opinion of the Linux raid author raid 10 seems to preform best while still having redundancy. You will loose 50% of your data storage but you will almost the same performance of RAID0 and redundancy of raid1.
For most up-to-date information regarding Linux software raid: https://raid.wiki.kernel.org/index.php/Overview
Raid10 level has multiple layout types. f(far)2 in tests seem to preform the best. Please see above link for references.
mdadm -v --create /dev/md0 --level=raid10 --layout=f2 --raid-devices=4 /dev/sda /dev/sdb /dev/sdc /dev/sdd
I am not using partitions on my disks, although there are reasons to use partitions, see here:
https://raid.wiki.kernel.org/index.php/Partition_Types
You can now monitor your raid (re)building: cat /proc/mdstat
Default the rebuild speed will be set and can be checked and changed here:
cat /proc/sys/dev/raid/speed_limit_max cat /proc/sys/dev/raid/speed_limit_min
make sure we have raid10 module loaded at boot
echo raid10 >> /etc/modules
When you are happy with your raid configuration, save its information to mdamd.conf file
mdadm --detail --scan >> /etc/mdadm.conf
It should display something like
ARRAY /dev/md0 metadata=1.2 name=scst:0 UUID=71fc93b8:3fef0057:9f5feec1:7d9e57e8
Monitor software raid
Linux software raid can be monitored with mdadm daemon option. Alpine Linux includes an initd script which can invoke the daemon
/etc/init.d/mdadm
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:
MAILADDR me@inter.net
Because mdadm cannot send email itself, we need to setup an sendmail (replacement) program.
apk add ssmtp
Ssmtp can be configured by editing /etc/ssmtp/ssmtp.conf
You can monitor messages (syslog) for actions invoked by mmdadm.
If you have your own monitoring system active, you can also let mdadm issue a script and notify it.