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Comment by wongarsu | Hacker News Reader

If you have one drive it feels like that, but if you throw 6+2 drives into a RAID6/raidz2. Sure, a full format can take 3 days (at 100 Megabytes/second sustained speed), but it's not like you are watching it. The real pain is fining viable backup options that don't cost an arm and a leg

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If your drives are only managing 100MB/s then something is wrong, SATA 3 should be at least 500MB/s.

SATA 3 can move 500MB/s, but high-capacity drives typically can't. They are all below 300MB/s sustained even when shiny new. Look for example at the performance numbers quoted in these data sheets [1][2][3][4], all between 248 MiB/s and 272 MiB/s.

Now that's still a lot faster than 100MB/s. But I have a lot of recertified drives, and while some of them make the advertised numbers some of them have settled at 100MB/s. You could argue that is something wrong with them, but they are in a raid and I don't need them to be fast. That's what the SSD cache is for.

1: Page 3 https://www.seagate.com/content/dam/seagate/en/content-fragm...

2: Page 2 https://www.seagate.com/content/dam/seagate/en/content-fragm...

3: Page 2 https://www.westerndigital.com/content/dam/doc-library/en_us...

4: Page 7 https://www.seagate.com/content/dam/seagate/assets/products/...

I had a 12 disk striped raidz2 array comprised of wd gold drives that could push 10Gbit/s over the network, while scrubbing, while running 10 virtual machines, and still had plenty of IO to play with. /shrug

Spinning rust drives tend to be much faster on the outer than the inner tracks.

Unfortunately, I’m absolutely watching it :-(

It happens whenever there is a progress indicator. I get obsessed with monitoring and verifying.

Unlike typical raid-5/6 parity, zfs / raidz doesn't require a format/parity initialization that writes all blocks of the disk before the pool can be used. You just need to write labels (at start & end of each disk) which is an attempt to confirm that the disk is actually as big as claimed.

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