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Update change documentation to reflect new single-pool design
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mfisher87 committed Nov 19, 2023
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## Storage changes

As a result of this incident, the failed 1TB HDD was replaced with a 1TB HDD in storage
pool 1. A new 4TB HDD was purchesd to replace this drive in pool 1, increasing its
capacity from 5TB (4TB + 1TB data + 4TB parity) to 8TB (4TB + 4TB data + 4TB parity).
The failed 1TB HDD was removed.

In addition, storage pool 2 was created from in stock 8TB disks to provide migration
space during recovery.
Pool 1 was grown by adding 4TB and 8TB data disks, and 2x 8TB parity disks, increasing
drive failure tolerance to 2.


## Deployment changes
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3 changes: 2 additions & 1 deletion changes/index.md
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---
title: "Changes"
listing: default
listing:
type: "table"
---
26 changes: 16 additions & 10 deletions nodes/storage.md
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Expand Up @@ -14,31 +14,37 @@ Upgraded over time and eventually migrated in to a Supermicro 12-bay hotswap cha
A total of 14 ports (6 motherboard SATA + 8 SAS expander PCI card). 12 are exposed as
hot-swap drive bays.

Hot-swap drives are largely exposed as _UnionFS_ drive pools, with parity provided by
SnapRAID.


### Pool 1

3x 4TB HDDs. 2 data disks totaling 8TB of storage. 1 parity disk (4TB).
A _UnionFS_ pool with *21TB* of storage capacity.

Redundancy provided by 2x _SnapRAID_ parity disks. Can tolerate 2 disk failures.


#### Data

* 3x 4TB HDDs
* 1x 8TB HDD
* 1x 1TB HDD


### Pool 2
#### Parity

3x 8TB HDDs. 2 data disks totaling 16TB of storage. 1 parity disk (8TB).
* 2x 8TB HDDs


### Considerations

When I add more disks, consider combining the pools. The current set up is to compromise
between maximizing available storage and tolerance for drive failures.
between maximizing available storage and tolerance for disk failures.

Pros:

* Can tolerate 1 drive failure, 2 if I'm lucky and they happen on separate pools.
* Can tolerate 1 disk failure, 2 if I'm lucky and they happen on separate pools.
* 24TB of storage available.

Cons:

* If two drives on the same pool fail, I'm in trouble. Combining the pool and having two
parity drives would allow two arbitrary drives to fail.
* If two disks on the same pool fail, I'm in trouble. Combining the pool and having two
parity disks would allow two arbitrary disks to fail.

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