* Should nossd mount option be used for an HDD detected as non-rotational?
@ 2019-07-13 9:22 R. Schwartz
2019-07-13 11:06 ` Andrei Borzenkov
0 siblings, 1 reply; 3+ messages in thread
From: R. Schwartz @ 2019-07-13 9:22 UTC (permalink / raw)
To: linux-btrfs
My HDD (one partition, BTRFS) reports itself as non-rational:
$ cat /sys/class/block/sda/queue/rotational
0
According to btrfs(5), by default, BTRFS detects this value and turns on
SSD optimizations for the HDD. Naturally, I'm puzzled...
My question is: should I use the nossd mount option for the HDD?
Following is more details about this HDD.
It's a recent Western Digital Blue 2TB HDD, model WD20EZAZ. Given its
cache size is a rather large 256MB, some people say it's likely an SMR
(shingled magnetic record) HDD.
Since Host-Managed and Host-Aware SMR HDDs support the `REPORT_ZONES`
ATA/SCSI command, I ran this test using `sg3_utils`:
# sg_rep_zones -R /dev/sda
Report zones command not supported
sg_rep_zones failed: Illegal request, Invalid opcode
Therefore, _if_ it's SMR, it must be Drive-Managed SMR.
So is there a good reason why the HDD reports itself as non-rotational?
Does it have to do with SMR?
Additioanlly, the HDD is connected through a SATA to USB connector. I
original suspected it was an issue with the connector, but I tested with
other HDDs with the same connector and they all report as rotational.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Should nossd mount option be used for an HDD detected as non-rotational?
2019-07-13 9:22 Should nossd mount option be used for an HDD detected as non-rotational? R. Schwartz
@ 2019-07-13 11:06 ` Andrei Borzenkov
2019-07-13 11:18 ` R. Schwartz
0 siblings, 1 reply; 3+ messages in thread
From: Andrei Borzenkov @ 2019-07-13 11:06 UTC (permalink / raw)
To: R. Schwartz, linux-btrfs
13.07.2019 12:22, R. Schwartz пишет:
> My HDD (one partition, BTRFS) reports itself as non-rational:
>
> $ cat /sys/class/block/sda/queue/rotational
> 0
>
> According to btrfs(5), by default, BTRFS detects this value and turns on
> SSD optimizations for the HDD. Naturally, I'm puzzled...
>
> My question is: should I use the nossd mount option for the HDD?
>
> Following is more details about this HDD.
>
> It's a recent Western Digital Blue 2TB HDD, model WD20EZAZ. Given its
> cache size is a rather large 256MB, some people say it's likely an SMR
> (shingled magnetic record) HDD.
>
> Since Host-Managed and Host-Aware SMR HDDs support the `REPORT_ZONES`
> ATA/SCSI command, I ran this test using `sg3_utils`:
>
> # sg_rep_zones -R /dev/sda
> Report zones command not supported
> sg_rep_zones failed: Illegal request, Invalid opcode
>
> Therefore, _if_ it's SMR, it must be Drive-Managed SMR.
>
> So is there a good reason why the HDD reports itself as non-rotational?
kernel sets non-rotational flag according to Medium Rotation Rate field
in Block Device Characteristics VPD page (0xb1). What
sg_vpd -p bdc /dev/xxx
says?
> Does it have to do with SMR?
>
> Additioanlly, the HDD is connected through a SATA to USB connector. I
> original suspected it was an issue with the connector, but I tested with
> other HDDs with the same connector and they all report as rotational.
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Should nossd mount option be used for an HDD detected as non-rotational?
2019-07-13 11:06 ` Andrei Borzenkov
@ 2019-07-13 11:18 ` R. Schwartz
0 siblings, 0 replies; 3+ messages in thread
From: R. Schwartz @ 2019-07-13 11:18 UTC (permalink / raw)
To: Andrei Borzenkov; +Cc: linux-btrfs
On Saturday, July 13, 2019 11:06 AM, Andrei Borzenkov <arvidjaar@gmail.com> wrote:
>
> kernel sets non-rotational flag according to Medium Rotation Rate field
> in Block Device Characteristics VPD page (0xb1). What
>
> sg_vpd -p bdc /dev/xxx
>
> says?
Block device characteristics VPD page (SBC):
Non-rotating medium (e.g. solid state)
Product type: Not specified
WABEREQ=0
WACEREQ=0
Nominal form factor: 2.5 inch
ZONED=0
RBWZ=0
BOCS=0
FUAB=0
VBULS=0
DEPOPULATION_TIME=0 (seconds)
Hmm, it also says 2.5 inch while it's a 3.5 inch drive.
Could be the connector though, methinks.
(Sorry, resent adding CC: ML)
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-07-13 9:22 Should nossd mount option be used for an HDD detected as non-rotational? R. Schwartz
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