5 ms·

RAID or not, if you lose an active drive you will need to 1) restore from backup, 2) fill a new backup drive If it takes days to fill your new 50 TB backup dri

by tux3 4y ago

RAID or not, if you lose an active drive you will need to 1) restore from backup, 2) fill a new backup drive If it takes days to fill your new 50 TB backup drive, you have the same problem RAID5 has with rebuild times. The drive might fail in the middle. RAID isn't a backup mostly because if you overwrite RAID data, you wrote over every copy at once. Non RAID offsite backups don't solve any problem related to drive size, they just make it a lot less likely for a single event to take everything out in the same minute.

cm2187 4y ago
Absolutely, you want RAID + backup, not one or the other. 50TB at 200MB/s is about 72h. Doesn't seem to be a particularly problematic rebuild time (and that's assuming 100% filled). Of course you need to do regular data scrubbing. If your rebuild is the first time the data is being read in 5y, that might not go so well.
- sn0wf1re 4y ago
  > 50TB at 200MB/s is about 72h. Assuming the device is offline for users during that time, otherwise there may be reduced throughput.
  - sroussey 4y ago
    Yes, and this can be quite painful. If you have standby sets (like a read replica of a db that can take over for master, or a DR site), you can switch temporarily. It’s good to know what throughput you have under load for this reason among others. Also, you can slow or pause some RAID during peak hours.
    - cm2187 4y ago
      But if we are talking about a NAS, hopefully you also have SSD caching which should reduce a lot the workload on your disks.
ThePowerOfFuet 4y ago
> RAID or not, if you lose an active drive you will need to 1) restore from backup RAID 1 joins the chat
sliken 4y ago
> RAID or not, if you lose an active drive you will need to 1) restore from backup Er what? I've had production machines lose a drive, have it replaced, and never leave production. Why would you need to restore from backups?
- tux3 4y ago
  Right, that was said very poorly. What I really wanted to express was that you need to fill a new drive either way, either by resilver or by making a new backup. Point one is bad, not sure why I wrote that!

by tux3 4y ago

cm2187 4y ago

Absolutely, you want RAID + backup, not one or the other. 50TB at 200MB/s is about 72h. Doesn't seem to be a particularly problematic rebuild time (and that's assuming 100% filled). Of course you need to do regular data scrubbing. If your rebuild is the first time the data is being read in 5y, that might not go so well.

sn0wf1re 4y ago
> 50TB at 200MB/s is about 72h. Assuming the device is offline for users during that time, otherwise there may be reduced throughput.
- sroussey 4y ago
  Yes, and this can be quite painful. If you have standby sets (like a read replica of a db that can take over for master, or a DR site), you can switch temporarily. It’s good to know what throughput you have under load for this reason among others. Also, you can slow or pause some RAID during peak hours.
  - cm2187 4y ago
    But if we are talking about a NAS, hopefully you also have SSD caching which should reduce a lot the workload on your disks.

ThePowerOfFuet 4y ago

> RAID or not, if you lose an active drive you will need to 1) restore from backup RAID 1 joins the chat

sliken 4y ago

> RAID or not, if you lose an active drive you will need to 1) restore from backup Er what? I've had production machines lose a drive, have it replaced, and never leave production. Why would you need to restore from backups?

tux3 4y ago
Right, that was said very poorly. What I really wanted to express was that you need to fill a new drive either way, either by resilver or by making a new backup. Point one is bad, not sure why I wrote that!