Arch Linux

SRG

Member

Registered: 2012-12-09

Posts: 69

Constant weird writes on a blank disk once partition is mounted

Hello,

I think i have a "possessed" HDD. I really don't understand what is happening.

I blanked it (i.e., i deleted the previous filesystem, recreated it, etc.).

As long as i don't mount the new filesystem, nothing is happening.

As soon as i mount the new filesystem, i have some writes continuously done against it.

If i umount the partition, no more activities.

Again : the filesystem is 100% empty.

I have not been able to find anything about what may generate the IO.

Any ideas ?

Detailled symptoms

I mount the disk with : mount /dev/sdg1 /mnt/
Then (it's an external HDD) i see the LED blinkings continuously.

With "iostat 2" i see constant activity over time (for hours) :

Device             tps    kB_read/s    kB_wrtn/s    kB_dscd/s    kB_read    kB_wrtn    kB_dscd
sdg             103.00       412.00         0.00         0.00        824          0          0
(...)
sdg               6.00         0.00      2566.00         0.00          0       5132          0
(...)
sdg               4.00         0.00      2048.00         0.00          0       4096          0

(some reads during a few seconds at the beginning, then continuous writes)

How i created the partition

mdadm --zero-superblock  /dev/sdg1 # see below

parted /dev/sdg --align optimal # then "mklabel gpt, mkpart with ... ext4 as FS ... start = 1 ... end = 100%

mkfs.ext4 /dev/sdg1

cfdisk /dev/sdg

                                                                                                              Disk: /dev/sdg
                                                                                           Size: 4.55 TiB, 5000981078016 bytes, 9767541168 sectors
                                                                                        Label: gpt, identifier: 34282417-3B4B-4EB0-830F-2DCCCF6DEEC0

    Device                                                           Start                                   End                                Sectors                              Size Type
>>  /dev/sdg1                                                         2048                            9767540735                             9767538688                              4.5T Linux filesystem                                   

Other informations

The disk was previously member of a MDADM array (from another computer) that i deleted (and of course i deleted / unmounted through mdadm before).
I did the same with other disks just before, without these symptoms.

The problem is still happening after reboot of the server, etc.

OS is ARCH up-to-date (kernel 6.18.X, etc.).

Analysis

- Nothing special in journalctl
- Nothing special in dmesg
- Nothing visible under "iotop" (only small activity from regular processes, nothing mapped on /dev/sdg)
- Nothing visible under "atop"
- Nothing visible under "fatrace -c" (when being in the mountpoint of /dev/sdg1)
- Nothing visible in "glances"

Any ideas ?

loqs

Member

Registered: 2014-03-06

Posts: 18,868

Re: Constant weird writes on a blank disk once partition is mounted

What if you mount the file-system with the option noinit_itable?

SRG

Member

Registered: 2012-12-09

Posts: 69

Re: Constant weird writes on a blank disk once partition is mounted

Ouch, that's it indeed ...

But what is puzzling me is the fact that it's the 3rd HDD that i'm plugging in the exact same way, and i haven't noticed anything for the two previous HDDs (no LED spinnings, etc. ... or the HDD were way faster to complete ?)

For reference :

mount -o noinit_itable /dev/sdg /mnt

Thanks for the direction.