6 ms·

Do you buy pairs of identical drives? If you want to be extra paranoid, you can use a pair of different models or at least different batches to reduce the risk

Do you buy pairs of identical drives? If you want to be extra paranoid, you can use a pair of different models or at least different batches to reduce the risk that they both fail in a short time window.

cbhl 6y ago
Latency is worse for non-identical drives, though, no?
- pixl97 6y ago
  Latency is as bad as the slowest drive operation. This said, even two identical drives can have different performance due to things like error rates or heat differences.
rbanffy 6y ago
I had a RAID-5 array of five identical, same batch and close serial numbers. One went bad. I ordered replacement and procurement blocked the purchase until I got it approved by my manager. I warned it was urgent. They delayed it for 3 days. On day 2, the second drive died. We had backups and could replay all db transactions up to the minute. Still, the service stopped for more than 24 hours. It took a week to clear the backlog.
- jonpurdy 6y ago
  Delayed approval of an urgent 3-figure purchase resulting in a 5-6 figure loss in productivity, customer sat, etc. Great example of penny-wise, pound-foolish!
  - rbanffy 6y ago
    Indeed. Small powers.
  - Spooky23 6y ago
    Buying individual drives to shave a few pennies is pretty foolish to begin with, so why stop there! Make it an OEM problem.
    - rbanffy 6y ago
      In their defense, we had a bunch of drives coming in in a month. It's just that we ran out of spares faster than expected (we had to increase capacity in a couple servers on short notice).
- driverdan 6y ago
  Hopefully they let you keep at least one new drive around as a backup after that experience. If you're not running RAID6 you should at least have one on the shelf, preferably from a different batch.
  - rbanffy 6y ago
    That was in 2003 or so. IIRC, mdadm didn't have raid6 support back then and the chassis wouldn't support more than 4 devices. Those were the heroic days.
- pilsetnieks 6y ago
  Honestly though, 1) the array rebuild might take that long time anyway; 2) the stress of the array rebuilding would probably make the other drive fail anyway.
yellowapple 6y ago
That's exactly what I do, except I take it a step further and go with different vendors.

cbhl 6y ago

Latency is worse for non-identical drives, though, no?

pixl97 6y ago
Latency is as bad as the slowest drive operation. This said, even two identical drives can have different performance due to things like error rates or heat differences.

rbanffy 6y ago

I had a RAID-5 array of five identical, same batch and close serial numbers. One went bad. I ordered replacement and procurement blocked the purchase until I got it approved by my manager. I warned it was urgent. They delayed it for 3 days. On day 2, the second drive died. We had backups and could replay all db transactions up to the minute. Still, the service stopped for more than 24 hours. It took a week to clear the backlog.

jonpurdy 6y ago
Delayed approval of an urgent 3-figure purchase resulting in a 5-6 figure loss in productivity, customer sat, etc. Great example of penny-wise, pound-foolish!
- rbanffy 6y ago
  Indeed. Small powers.
- Spooky23 6y ago
  Buying individual drives to shave a few pennies is pretty foolish to begin with, so why stop there! Make it an OEM problem.
  - rbanffy 6y ago
    In their defense, we had a bunch of drives coming in in a month. It's just that we ran out of spares faster than expected (we had to increase capacity in a couple servers on short notice).
driverdan 6y ago
Hopefully they let you keep at least one new drive around as a backup after that experience. If you're not running RAID6 you should at least have one on the shelf, preferably from a different batch.
- rbanffy 6y ago
  That was in 2003 or so. IIRC, mdadm didn't have raid6 support back then and the chassis wouldn't support more than 4 devices. Those were the heroic days.
pilsetnieks 6y ago
Honestly though, 1) the array rebuild might take that long time anyway; 2) the stress of the array rebuilding would probably make the other drive fail anyway.

yellowapple 6y ago

That's exactly what I do, except I take it a step further and go with different vendors.