What is the difference between RAID 0 and RAID 1?

[markrad]

Hello,

I bought a new server, which has 2x 960 SSD NVMe as Raid 1 by default. I think that Raid 1 is a good choice for me, as I have a separate server for backups (every day). If I want to consider Raid 1 as a backup, what are the other cons of Raid 1 vs Raid 0 in terms of redundancy?



P.S. If one disk in my server is damaged, will the server still be able to work without any downtime on Raid 1?

 

[bobmc]

raid 1 is a mirrored setup, each nvme drive is a full copy of the other so if one fails, the system can continue to function.

raid 0 is a striped setup, each nvme drive holds only half of the data so if one fails, the system will fail and all data is lost. The reason why raid 0 exists is that it offers higher performance but you need to accept an increased risk of data loss.

 

[markrad]

@bobmc this is RAID 1 in PROXMOX?

 

[bobmc]

no, this effectively is raid0 because you only have two devices. raid10 is both striped and mirrored but you need 4 devices to make this work as intended.

 

[markrad]

@bobmc I don't see raid0

 

[bobmc]

You should choose Mirror in that menu

 

[Dunuin]

Raid0 is "Singe Disk" in that dropdown. Raid1 is "Mirror".

 

[bbgeek17]

If I want to consider Raid 1 as a backup

RAID is not a backup https://www.raidisnotabackup.com/

what are the other cons of Raid 1 vs Raid 0 in terms of redundancy

There cannot be any cons as Raid0 has exactly 0 redundancy. If you loose one disk - you loose all data.
https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_0

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[markrad]

@bobmc, @Dunuin, @bbgeek17

Thanks for the help!

When I have a second server with only a virtual desktop and not important files, is RAID not necessary, right?

I want using raid for:
Raid 1 mirror for stuff that need uptime (vm host, router, NAS etc) Raid 0 stripe for large datasets you can wait for restore from backup (fileshares, backupvault etc).

It is okay?

 

[markrad]

@bobmc @Dunuin @bbgeek17

I talked with OVH, and when one disk is damaged, OVH turns off the whole server and replaces the disk.

In this situation, is RAID 1 required? Is the only benefit of RAID 1 that it copies onto the second disk and can quickly run the server again? Yes?

 

[Dunuin]

With raid1 your server will continue running when a disk fails, so no unplanned downtime. The server won't crash, you won't lose data (otherwise at least the data since the last backup would be lost) and you got less work to do because you don't have to install+configure PVE again. And in case of ZFS a raid1 would also protect you from bit rot.

So if you care about your data or downtime a raid0 should never be a consideration.