Dynamic Storage Solution
Hi,
Can someone tell me about a good way to create a storage solution with several disks? I want some redundancy like RAID5 so that if a disk fails, data isn't lost and if I have not enough space, it should be possible to add more disks.
If RAID5 is the best way to go, can someone show me the way to a good dummy level tutorial (manual)?
Thanks in advance.
Greetz
Filips
Can someone tell me about a good way to create a storage solution with several disks? I want some redundancy like RAID5 so that if a disk fails, data isn't lost and if I have not enough space, it should be possible to add more disks.
If RAID5 is the best way to go, can someone show me the way to a good dummy level tutorial (manual)?
Thanks in advance.
Greetz
Filips
I would suggest that you run LVM on top of a RAID 5 system. This way you have the advantages of a RAID system, butyou can also add more space if you need it: http://www.aplawrence.com/Linux/lvm.html
BTW: LVM is the Linux Volume Manager, this HOWTO explains pretty much everything about it: http://www.tldp.org/HOWTO/LVM-HOWTO/
ASKER
Question: will the to the LVM added disks covered by the RAID5. That is; when I have disk sda, sdb, sdc, sdd and sde in a raid 5 and I add a disk sdf to LVM and afterwards sdf fails and I replace the disk, will the data still be there?
Do I have to use RAID or is LVM alone enough?
Thanks in advance.
Greetz
Filips
Do I have to use RAID or is LVM alone enough?
Thanks in advance.
Greetz
Filips
LVM and RAID a *pretty much* the same things. At least, the same concepts.
RAID stands for Redundant Array of Independent Disks. There are different levels of RAID.
Basically :
- RAID1 is mirroring. This means that you have to use twice the disk space.
- RAID5 is the luxury RAID as it's the level for which parity bits are scattered across all disks. Its a bit expensive in terms of IO (slows the disk access down), but it allows you to "burn" any ONE of the disks, replace it, and rebuild without any data loss.
For more infos, have a look here :
http://www.raidweb.com/whatis.html
Hardware RAID implementations sometimes also allow "hot-swapping". This means that you can take off a disk even if the array is powered up. Thus replacing a disk without stopping the system.
LVM is just a (free) software implementation of different RAIDs. It's slower than a hardware implementation, but implemented in Linux at the kernel level.
So, it's your choice of which RAID you want to implement with LVM. The above suggestion of RAID5 by khkremer is good. You basically spare 1/5 of your disk space, but it's worth it if you need it.
So, to answer your question, all the disks you add to the RAID config will participate in your RAID array. And if ANY one of them fails (one at a time !), you should be able to replace it without any data loss.
RAID stands for Redundant Array of Independent Disks. There are different levels of RAID.
Basically :
- RAID1 is mirroring. This means that you have to use twice the disk space.
- RAID5 is the luxury RAID as it's the level for which parity bits are scattered across all disks. Its a bit expensive in terms of IO (slows the disk access down), but it allows you to "burn" any ONE of the disks, replace it, and rebuild without any data loss.
For more infos, have a look here :
http://www.raidweb.com/whatis.html
Hardware RAID implementations sometimes also allow "hot-swapping". This means that you can take off a disk even if the array is powered up. Thus replacing a disk without stopping the system.
LVM is just a (free) software implementation of different RAIDs. It's slower than a hardware implementation, but implemented in Linux at the kernel level.
So, it's your choice of which RAID you want to implement with LVM. The above suggestion of RAID5 by khkremer is good. You basically spare 1/5 of your disk space, but it's worth it if you need it.
So, to answer your question, all the disks you add to the RAID config will participate in your RAID array. And if ANY one of them fails (one at a time !), you should be able to replace it without any data loss.
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Hem... Please ignore my whole comment. I mixed up lvm with md :-(
I'm going back to bed. Flu and computers don't mix so well...
I'm going back to bed. Flu and computers don't mix so well...
ASKER
Alf666, get better soon. I need you here.
ASKER