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They're not going to be skewed. HGST disks are usually more expensive, so that limits the quantity that they buy. The seagate disks are usually cheaper but ha

They're not going to be skewed. HGST disks are usually more expensive, so that limits the quantity that they buy. The seagate disks are usually cheaper but have a slightly higher (except when it's a brand new line) failure rate. When filling out a single server I go with the HGST disks because the premium price and quality means fewer failures, but it's more cost effective to go for lots of seagate disks when you have more redundancy and can eat more failures.

level 8y ago
I built a server a few years ago, and I determined it was more cost effective for a drive to fail than to use HGST. It would be more inconvenient, but having a drive fail on a home server with only 6 drives didn't seem very likely anyway.
- cm2187 8y ago
  Particularly if it fails within the warranty period.
- jacobolus 8y ago
  If you have a 2%/year failure rate per drive, then that leaves you with a nearly 12%/year chance that at least 1 of 6 drives will fail each year. Or a 31% chance that at least 1 of 6 drives will fail within 3 years. Or a 52% chance that at least 1 of 6 drives will fail within 6 years.
  - sangnoir 8y ago
    The question then is, would it be cheaper to replace that one drive or get the more expensive disks with lower chances of failing?
    - Arn_Thor 8y ago
      Isn't there a cost to time and convenience too? Buying a new disk takes time, as does rebuilding the RAID. And during that time you are vulnerable to another drive failure which could be disastrous if you only have one drive redundancy, especially during the very intensive rebuilding process.
- simcop2387 8y ago
  There's also the cost of the time it takes you to replace the drive, get it replaced under warranty, etc. that takes a part of the cost of everything too. I decided that the (at the time) marginal cost of $20/disk was worth my time in likely not having to deal with it.
VectorLock 8y ago
This makes me curious of where the cost/benefit point is between these brands of drives. Do they buy enough that the reduced cost for higher failure rate outweighs the expense of buying more expensive drives?
- fludlight 8y ago
  It's only partially a question of quantity. The larger factor is the amount of labor involved in dealing with a bad drive. Their (large) operation seems automated so I assume if they have a single drive failure in machine #1234 (which has 50+ drives) they have an automated way of switching off said drive. Then they leave it there until the entire rack is replaced many years later. Other operations have to send a human to manually replace every single failed drive as soon as it fails, which is very expensive as a % of the cost of the bare drive.
- simcop2387 8y ago
  They buy enough drives that there's another point of data that's needed for them. Availability of the disks. If they need to expand a few 10s of petabytes they may only be able to get enough disks from one group regardless of reliability concerns.
  - VectorLock 8y ago
    Thats what surprised me when I learned that they were "shucking" drives from off the shelf external drives at some point.
zepearl 8y ago
I agree (about Seagate being more cost effective for e.g. a datacenter). As private user I had in general bad experiences with Seagate (e.g. years ago I bought 8 2TB drives for 2 raid5 and 2 didn't even spin up, 1 failed after ~1 year) => I'm using since then only HGST and (pls. no jinx) so far only 1 has failed, but it "warned me in advance" with weird noises and terrible performance for ~1 week or so. I now have at hetzner.de a host that has 3 4TB Seagate drives and I ended up building a 3-disks-raid1 instead of a raid5 because I'm too scared that when one drive fails, an additional one will fail as well during the rebuild-process when the remaining ones are stressed (a raid5 would then implode in this situation).

level 8y ago

I built a server a few years ago, and I determined it was more cost effective for a drive to fail than to use HGST. It would be more inconvenient, but having a drive fail on a home server with only 6 drives didn't seem very likely anyway.

cm2187 8y ago
Particularly if it fails within the warranty period.
jacobolus 8y ago
If you have a 2%/year failure rate per drive, then that leaves you with a nearly 12%/year chance that at least 1 of 6 drives will fail each year. Or a 31% chance that at least 1 of 6 drives will fail within 3 years. Or a 52% chance that at least 1 of 6 drives will fail within 6 years.
- sangnoir 8y ago
  The question then is, would it be cheaper to replace that one drive or get the more expensive disks with lower chances of failing?
  - Arn_Thor 8y ago
    Isn't there a cost to time and convenience too? Buying a new disk takes time, as does rebuilding the RAID. And during that time you are vulnerable to another drive failure which could be disastrous if you only have one drive redundancy, especially during the very intensive rebuilding process.
simcop2387 8y ago
There's also the cost of the time it takes you to replace the drive, get it replaced under warranty, etc. that takes a part of the cost of everything too. I decided that the (at the time) marginal cost of $20/disk was worth my time in likely not having to deal with it.

VectorLock 8y ago

This makes me curious of where the cost/benefit point is between these brands of drives. Do they buy enough that the reduced cost for higher failure rate outweighs the expense of buying more expensive drives?

fludlight 8y ago
It's only partially a question of quantity. The larger factor is the amount of labor involved in dealing with a bad drive. Their (large) operation seems automated so I assume if they have a single drive failure in machine #1234 (which has 50+ drives) they have an automated way of switching off said drive. Then they leave it there until the entire rack is replaced many years later. Other operations have to send a human to manually replace every single failed drive as soon as it fails, which is very expensive as a % of the cost of the bare drive.
simcop2387 8y ago
They buy enough drives that there's another point of data that's needed for them. Availability of the disks. If they need to expand a few 10s of petabytes they may only be able to get enough disks from one group regardless of reliability concerns.
- VectorLock 8y ago
  Thats what surprised me when I learned that they were "shucking" drives from off the shelf external drives at some point.

zepearl 8y ago

I agree (about Seagate being more cost effective for e.g. a datacenter). As private user I had in general bad experiences with Seagate (e.g. years ago I bought 8 2TB drives for 2 raid5 and 2 didn't even spin up, 1 failed after ~1 year) => I'm using since then only HGST and (pls. no jinx) so far only 1 has failed, but it "warned me in advance" with weird noises and terrible performance for ~1 week or so. I now have at hetzner.de a host that has 3 4TB Seagate drives and I ended up building a 3-disks-raid1 instead of a raid5 because I'm too scared that when one drive fails, an additional one will fail as well during the rebuild-process when the remaining ones are stressed (a raid5 would then implode in this situation).