On Thu, 21 Nov 2019 01:16:16 -0500, Brian <b_li...@patandbrian.org> wrote:
>Hi all, > >Running Ubuntu 18 LTS, I have a console-mode number-cruncher which >writes occasional output files. It works just fine if the output is >directed to a drive which is permanently spun up, but can fail if the >output is directed to a USB drive (by which I mean a USB-connected 8TB >external drive, not one of the keydrives). I've followed things >through with the debugger, and it seems that the problem occurs when >the drive has powered itself down due to lack of accesses. The assign >and rewrite work OK, but then the first attempt to write to the file >fails with a 'No such file' error. Putting a large (30 second!) delay >before the first write means everything works OK, presumably because >the drive gets time to spin up again. > >My question: Is there a standard method for handling this situation, >i.e. making sure that a drive has not spun down, or is it just a case >of writing a wrapper round the write function and handling the 'No >such file' error with a wait and a retry? > Maybe not a solution here but I have experienced the same kind of problem on my Windows 7 laptop where I have a 2TB data drive where all my work is being done. Compilations and other similar tasks were annoyingly slow to start when I discovered that Windows7 had spun down the drive and no matter what I did to change settings it would not stay running. So I created a very small FPC program that writes and reads back one byte to a file on the drive every 10 seconds and measures the latency (using gettickcount) to use to display the max/min and average delays. When this is running (it is in my startup) I no longer have these startup problems of the drive. Right now it has accumulated 35510 access time values which average 15 ms with a max of 327 ms. All since the last reboot. -- Bo Berglund Developer in Sweden _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
