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I can write ~100MB/s on a particular 4TB SAS drive when it have a file system on it, but a low level format on this drive took >16 hours. That's ~70kB/s. Since there is not filesystem and only zeroes have to be written, I would have expected better performance then with a filesystem.

The LLF was done in a HP MDS600 (D6000) JBOD in its onboard RAID utility.


Why does a low level format take so long?

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Question: Why do you do a low-level format? And how do you do that? – Sven Jul 27 '14 at 10:48
Opdated OP with method. The LLF was done in a HP MDS600 (D6000) JBOD in its onboard RAID utility. – Jasmine Lognnes Jul 27 '14 at 10:56
Do you wan't to do this as a data wipe operation? Low level formats aren't necessary for around two decades now. – Sven Jul 27 '14 at 11:03
You don't need to perform low-level formats on the types of drives you're using, nor is it necessary for what you're planning to do. – ewwhite Jul 27 '14 at 13:30
and only zeroes have to be written. No, that is not true. a high level format might write a filesystem with zeros on it (the zeros as content plus FS tables). A low level will have to write sync markers, sector headers, some (empty, zero'd?) sector content and possibly a CRC. It has to do that for each sector. It will also need to write the spare sectors (in case a sector goes bad and needs to be remapped) and some internal tables. That is not the same as only zero's. – Hennes Jul 27 '14 at 15:23
up vote 3 down vote accepted

If performing a low-level format on a 4TB drive takes 16 hours, it's formatting at a rate 70MB/s. That's comparable to the 100MB/s at which you say you can normally write to the drive.

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Additionally, some LLF's will read the data back after writing. – Dan Jul 27 '14 at 12:27

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