Re: seagate hm-smr issue

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 2021/09/27 8:42, Jingyun He wrote:
> Hi,
> You are correct, for a WD/HGST HM-SMR disk, it takes about 15 mins to
> mount a full disk.
> 
> But It takes about 2-3 hours for mounting a Seagate HM-SMR disk.
> 
> Have no idea why Seagate takes so loooooong time.

This is most likely due to a difference in the execution time of report zones
commands.

In any case, this will be resolved soon as we can cache a full disk zone report
during the mount operation to avoid this slow per-zone report operation.

> 
> On Mon, Sep 27, 2021 at 7:13 AM Damien Le Moal
> <damien.lemoal@opensource.wdc.com> wrote:
>>
>> On 2021/09/26 22:57, Jingyun He wrote:
>>> Hello,
>>> Btrfs works very well on WD/HGST disks, we got some Seagate HM-SMR
>>> disks recently,  model number is ST14000NM0428,
>>> mkfs.btrfs works fine, and I can mount it, and push data into disk.
>>> once we used up the capacity, and umount it. then we are unable to
>>> re-mount it again.
>>> The mount process will never end, the process just hangs there.
>>>
>>> Anybody can help me with this?
>>
>> +Naohiro and Johannes
>>
>> This is not a hang. Mount will just take a looooong time due to an inefficiency
>> in how block groups are checked: a single zone report zone command is issued per
>> block group, so with a disk almost full, that takes a long time (75000+zones
>> checked one by one). Naohiro is working on a fix for this.
>>
>>>
>>> Thanks.
>>>
>>
>>
>> --
>> Damien Le Moal
>> Western Digital Research


-- 
Damien Le Moal
Western Digital Research