Third Party > Unsupported Builds
[share]custom rockbox build for SSDed ipod6g(classic)
r4bbit:
--- Quote from: saratoga on March 05, 2017, 01:32:54 PM ---His SSD is probably not made for use in a DAP that will go 30 minutes at a time without accessing it, so it probably powers off and has to reboot when he access it again. The stock hard drives are made to work for portable devices so they are always ready to talk to the host.
--- End quote ---
this is not the case.the disk failure happens pretty randomly.it may happen in 30 seconds after i powered on my device.
--- Quote from: Massa on March 05, 2017, 12:45:15 PM ---Hmm, I don't get it - why does doubling a timeout value make it more reliable for SSDs?
Aren't SSD faster than HDs and therefore shouldn't need longer timeouts? ???
I'm confused!
--- End quote ---
yes,the overall speed of ssd is almost always faster than hdd.no matter compared by 4k random write or by sequence write.but a disk write consists a few micro operation at lower level.
i assume at driver level there should be two mirco operations: 1.seek for a track. 2.write data to track , each of them has its own timeout value.
the seeking operation of ssd should be much faster than hdd and will never timeout. the write operation of ssd may be slower,because of the "write amplification" effect of writting a nand and the "wear leveling" work of the ssd's chip.
there is a ssd 4k random write latency test picture in attachment,its not tested on my ssd,its from internet.the highest latency of a 4k write can be 30ms when the ssd is 75% filled,and it become worse after 100% filled,as high as 40 ms.the seeking time of ssd is about 0.1ms,so you can ingore the seek time and consider the overall time as the time of doing write.
for hdd,after the track has been seeked,the write latency shouldnt be higher than spinning a round(which is 60min/4200RPM=14.3ms).
i m not an expert of disk driver. i was just analyzing ;D
prof_wolfff:
There are situations where writing a sector to a SDD takes more time, it is depending on the wearing algorithms and the block size of the SDD, i.e. when writing a sector requires to reallocate other sectors, or when there are free sectors but they are not erased, then the SDD FW needs to erase a whole block before writing this sector. It is supposed that the SDD FW will do these operations on background when the SDD is idle but not always is possible to do that way, or the FW algorithms are not good enough.
clembo:
I have an Ipod 4G with the exact same type of behaviors when using an SD card as r4bbit has on his Ipod 6G.
Long/short. I have a working 32GB Adata CF card that works fantastic; it's connected via a CF to Mini IDE. I was very careful to make sure it emulated a hard drive. Later on I picked up 2 additional Ipod 4G's, did the same process only change is that I decided to experiment with a CF to SD adapter instead of a CF card. This is where I ran into errors; tried multiple different storage sizes/speeds and got the same result. I suppose there are a few different approaches that one could take, but I'd rather use an SD card (much more convenient and cheaper than CF).
I can restore the Ipod, install play/stop music using Itunes on the Ipods. I can install and load rockbox w/out issue. The trouble starts when attempting to write to the SD card while in Rockbox. To duplicate, I attempted to save the CFG file within settings. It takes a long time to write and then errors out with a kernel panic.
Here's a copy of the error message:
Panic
sc_writeback_callback ()_ could not write sector 152315 (error -4)
pc:0006504C sp:400B930
A:00073868
BT end
@r4bbit
I'm going to try the same approach you did and see if that resolves the write issue.
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