sda: asking for cache data failed

[dutchbb1979]

We just upgraded our server with 8 brand new seagate cheetah 15k.5's, a battery backup unit,
and a 256mb dimm for the raid controller. In the boot process, i noticed an error about caching or something.

After analyzing the dmesg log, i found the error:
sda: asking for cache data failed
sda: assuming drive cache: write through

It seems like the kernel can't get to the raid controllers cache, so it switches to the write through setting.
I've benchmarked the harddisks with the write through, and write back setting. The odd thing is that both settings deliver the same performance.
Normally, write back increases the performance with like 100%... That's why we bought the battery backup unit.
So something is going wrong, but where lays the problem?


Server:

8 X seagate cheetah 15k.5, U320, 16mb cache, SCA, 73GB
1 X chenbro backplane, U320, SCA, 2 channels, 8 ports
1 X LSI megaraid 320-2x raid controller, U320, 2 channels, battery pack and 256 upgraded dimm
6 GB DDR PC3200, ECC, CL3
2 X AMD opteron dual cores (4 X 2.0 ghz)

[stugs]

We just upgraded our server with 8 brand new seagate cheetah 15k.5's, a battery backup unit,
and a 256mb dimm for the raid controller. In the boot process, i noticed an error about caching or something.

After analyzing the dmesg log, i found the error:
sda: asking for cache data failed
sda: assuming drive cache: write through

It seems like the kernel can't get to the raid controllers cache, so it switches to the write through setting.
I've benchmarked the harddisks with the write through, and write back setting. The odd thing is that both settings deliver the same performance.
Normally, write back increases the performance with like 100%... That's why we bought the battery backup unit.
So something is going wrong, but where lays the problem?


Server:

The kernel asks the SCSI drive for its cache parameters. The raid
card sitting in the middle doesn't know how to handle this so this
message occurs. It should be ok providing the raid card itself is
handling the consistency correctly but check with your card vendor.

[dutchbb1979]

Yes I've contacted the vendor but no reply yet.


Anyone else who knows about this problem?

[johnbrown362003]

That message is harmless.
http://lists.us.dell.com/pipermail/l...ly/026434.html

Also, make sure you apply the latest firmware for the Seagate Drives. Over the last few years, Dell has issued a couple of firmware updates for the Seagate 320 drives - the faulty firmware on the drives is what caused the drives to randomly fall offline or hang. (No firmware problems with the Fujitsu 320 drives from Dell but Dell no longer uses the Fujitsu 320 drives.)