Software projects/OS/Slackware/Advanced usage/RAID
From Pandora Wiki
- 1 WIP WIP WIP HURRAID
- 2 RAID
- 3 Partitioning
- 4 Card 1
- 5 Card 2
- 6 Install SL4P
- 7 Backup /srv
- 8 Finalizing card 1 setup
- 9 Finalizing card 2 setup
- 10 Create the RAID 1 array
- 11 Format the RAID array
- 12 Make the RAID configuration permanent
- 13 Final step
- 14 Some Practice
- 15 Remove a drive from the array
- 16 Repair the array
WIP WIP WIP HURRAID
- Need to properly rebuild one array while completing this Wiki section.
- For now, don't try this incomplete tutorial unless you have some RAID knowledge
- Once finished and this warning removed, go for it.
- We will use the robust native Linux software RAID.
- It's a feature that can be used on the Pandora, so let's have fun with it
- I will cover here only a RAID 1 (mirror) on two SD cards, as it should be the more interesting for a server usage because under read load, you should reach about 27MB/s against 16MB/s on one card.
- A SD + USB drive can also work although untested. Same with a two SD + USB drive configuration.
- This array will be mounted as /srv , the standard server folder.
- So you have to partition your system SD card a bit differently than the default SL4P setup.
- In this example, we will use the recommended minimal 8G card for the slot 1.
- You can use a different sized card for the right slot. To keep thing interesting, the minimum size is 4G for this second card, and we will use 4G in this example.
- The RAID 1 partitions must have the same exact size.
- Partition that way:
6G ext2 for the system. 256M for the swap.
That's all for now, the third partition will be created under Slackware, and will be:
- We will left 256M free. NEVER fill an entire drive with a RAID array. Drives, ie. all 8G, doesn't necessary offer the same exact capacity, so you can get in trouble if you add a drive 32MB short.
256M for the swap. Having swap on two different cards is a good thing.
That's all for now, the other partitions will be created under Slackware, and will be:
1.5G unformated RAID. 2G unused. Do what you want with it.
- Uncompress the rootfs on the first SD card, first partition, put the card in your OP, and boot it.
- Log in.
- As root:
mkdir /srv-save mv /srv/* /srv-save/
Finalizing card 1 setup
- If you don't know how to use cfdisk, please read this first.
- As root:
Finalizing card 2 setup
- As root:
Create the RAID 1 array
- Load module ?
- The RAID devices names are md0, md1, md2 etc..
mdadm --create /dev/md0 --level 1 --raid-devices 2 /dev/mmcblk0p3 /dev/mmcblk1p2
Format the RAID array
- As usual, we choose the Linux extended 2 filesystem.
Make the RAID configuration permanent
mdadm --scan > /etc/mdadm.conf
Edit /etc/fstab and add these lines:
/dev/mmcblk1p1 swap swap defaults 0 0 /dev/md0 /srv auto defaults,noatime 1 1
- As root:
mount/dev/md0 mv /srv-save/* /srv/ rm -rf /srv-save/
- That's it, you have now a RAID 1 array on your Pandora :^).
- If you want to know how to repair a RAID array, let's simulate a failure.
Remove a drive from the array
- It's likely to be the one in the right SD slot.
- Unmount the swap:
Repair the array
- Depending the size of your RAID partition and he data on it, it can take a while.
- Mount the swap: