I purchased two WD Ultrastar DC HC550 18TB drives and wanted to do some thorough testing before starting to use them, so I'm following the advice in qwertymodo's post that started this thread
But... it's taking forever, even though I'm testing both disks in parallel.
The long S.M.A.R.T. test took roughly 30 hours. Then I started badblocks. The first pattern (0xaa) took roughly 46 hours. Now at 49h40m they're 16.6% and 20.4% along writing the 0x55 pattern, but at 100% they'll start "Reading and comparing" 0x55 before moving on to 0xff and then 0x00.
(I find it a bit interesting that one drive appears faster than the other, since I started badblocks on the two drives just 10 seconds apart.)
So badblocks looks like it'll take around 180 hours, or a bit over 7 days. That's a long wait. And after that qwertymodo's post says I should run another long S.M.A.R.T. test, for another 30 hours. That'll be a total of roughly 10 days' worth of testing the drives before starting to use them.
I didn't notice the difference that the
flag to badblocks potentially can make until after around 30 hours or so, and at that point I was very hesitant to abort badblocks to try out different
values to see if I got a speedup. If there's no speedup, that'll mean I've aborted and had to restart badblocks for nothing, losing a lot time.
How thorough do you guys test large drives before starting to use them? And what flags do you use?
Also, while on the subject of badblocks: for large drives a larger block size must be used, apparently due to some 32 bit limitations in the code. qwertymodo advises to use
for drives larger than 2TB. Well, I had to use
for the 18TB drives, as I first got errors:
root@nas:~ # time badblocks -ws /dev/ada0
badblocks: Value too large to be stored in data type invalid end block (17578328064): must be 32-bit value
0.000u 0.003s 0:00.00 0.0% 0+0k 0+0io 0pf+0w
root@nas:~ # time badblocks -b 4096 -ws /dev/ada0
badblocks: Value too large to be stored in data type invalid end block (4394582016): must be 32-bit value
0.000u 0.005s 0:00.02 0.0% 0+0k 0+0io 10pf+0w
root@nas:~ # smartctl -a /dev/ada0 | grep 'Sector Sizes:'
Sector Sizes: 512 bytes logical, 4096 bytes physical
But I read somewhere (can't find the source now) that using a block size larger than the drive's sector sizes was bad/pointless, since that somehow wouldn't test the entire disk, i.e. using a 8192 bytes block size on a drive with sector size 4096 bytes meant that only every other 4096 bytes would actually be tested.
Anyone knows if this is correct? If it is, it means I'm really just wasting time running badblocks.