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GeorgeJP

Member

From: Czech Republic

Registered: 2020-01-28

Posts: 186

[SOLVED] SSD drive cache - new err msg in 5.15.5

Hi, I have new error messages during boot.
In previous kernel versions there was only message in journal.
Are they harmless?

Kernel <= 5.15.4

lnb kernel: scsi 0:0:0:0: Direct-Access     ATA      Samsung SSD 840  5B0Q PQ: 0 ANSI: 5
lnb kernel: sd 0:0:0:0: [sda] 500118192 512-byte logical blocks: (256 GB/238 GiB)
lnb kernel: sd 0:0:0:0: [sda] Write Protect is off
lnb kernel: sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
lnb kernel: sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA

Kernel = 5.15.5

lnb kernel: scsi 0:0:0:0: Direct-Access     ATA      Samsung SSD 840  5B0Q PQ: 0 ANSI: 5
lnb kernel: sd 0:0:0:0: [sda] 500118192 512-byte logical blocks: (256 GB/238 GiB)
lnb kernel: sd 0:0:0:0: [sda] Write Protect is off
lnb kernel: sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
lnb kernel: sd 0:0:0:0: [sda] Asking for cache data failed
lnb kernel: sd 0:0:0:0: [sda] Assuming drive cache: write through

Edit: resolved in kernel 5.15.6

Last edited by GeorgeJP (2021-12-03 22:40:10)

blablo

Member

Registered: 2011-06-02

Posts: 38

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

https://bugzilla.kernel.org/show_bug.cgi?id=215137

GeorgeJP

Member

From: Czech Republic

Registered: 2020-01-28

Posts: 186

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

https://bugzilla.kernel.org/show_bug.cgi?id=215137

Thanks, caused most probably by:

https://git.kernel.org/pub/scm/linux/ke … 43dc1b5851

Last edited by GeorgeJP (2021-11-26 18:37:51)

merlock

Member

Registered: 2018-10-30

Posts: 235

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

Yeah, I noticed the same thing...2 SSD's, and one spinner.

---

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Vizitor

Member

Registered: 2015-01-05

Posts: 81

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

Are they harmless?

I have those messages on sda, sdb, sdc, sdd;
So, are they harmless?

--Edit--
I found this

What do the Asking for cache data failed and Assuming Drive Cache: write-through messages mean?
Hard disks have a small amount of RAM cache to speed up write operations. The system can write a chunk of data to the disk cache without actually waiting for it to be written to the disk. This is sometimes called "write-back" mode.

If there is no cache on the disk, data is directly written to it in "write-through" mode.
The Asking for cache data failed warning usually occurs with devices such as USB flash drives, USB card readers, etc. which present themselves as SCSI devices to the system (sdX), but have no cache.

The system asks the device: "Do you have a cache?" and gets no response. So it assumes there is no cache and puts it in "write-through" mode.

So, as I understand, it is a performance issue, but data is safe?

Last edited by Vizitor (2021-11-29 10:29:30)

mokkurkalve

Member

From: Bergen, Norway

Registered: 2009-08-29

Posts: 60

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

I certainly hope this would cause more stir if there were danger of data corruption. Anyway, I did compile my kernel with c749301ebee82eb5e97dec14b6ab31a4aabe37a6.patch to fix this. Let's hope the fix goes into 5.15.6.

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"ONLY THOSE WHO ATTEMPT THE IMPOSSIBLE WILL ACHIEVE THE ABSURD"
- Oceania Association of Autonomous Astronauts

Vizitor

Member

Registered: 2015-01-05

Posts: 81

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

I did compile my kernel with c749301ebee82eb5e97dec14b6ab31a4aabe37a6.patch

I installed linux-lts on nvidia based computer, so

Failed to unmount /oldroot: Device or resource busy

and

Asking for cache data failed

are "killed with one stone"

But, on computer with 'AMD RX 6700XT VGA' linux-lts I can't get screen to work, because kernel 5.10 is too old, so I leave it on default arch 'linux' kernel, hoping there will be fix in the next kernel update(s).

mokkurkalve

Member

From: Bergen, Norway

Registered: 2009-08-29

Posts: 60

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

Failed to unmount /oldroot: Device or resource busy

I don't know what this problem is. I don't seem to have it.

---

"ONLY THOSE WHO ATTEMPT THE IMPOSSIBLE WILL ACHIEVE THE ABSURD"
- Oceania Association of Autonomous Astronauts

BachoSeven

Member

Registered: 2020-04-16

Posts: 9

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

@mokkurkalve I can confirm to also see the `Failed to unmount /oldroot: Device or resource busy` since the latest (or `5.15.4`) zen kernel update (might also be due to another package upgrade, though.)

Last edited by BachoSeven (2021-11-29 11:56:26)

Vizitor

Member

Registered: 2015-01-05

Posts: 81

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

I don't know what this problem is. I don't seem to have it.

Ah, nevermind that, it is an error that I have from previous kernel version(s)

loqs

Member

Registered: 2014-03-06

Posts: 17,369

Re: [SOLVED] SSD drive cache - new err msg in 5.15.5

Fix is queued for 5.15.6 https://git.kernel.org/pub/scm/linux/ke … c6c16abfe7