Date: Mon, 24 Dec 2001 16:21:58 +1000 From: "Andrew Hannam" <famzon@bigfoot.com> To: <freebsd-small@freebsd.org> Subject: Disk Writes Message-ID: <003d01c18c43$5446ad20$0104010a@famzon.com.au>
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I have been doing some embedded work based on Free/PicoBSD based on a 4.2 kernel but have come across a problem that is showing it's head occasionally. We are currently in the process of rolling out 1000 devices (currently at 75) over the next 6 months. Fortunately I have the ability to upgrade the devices in the field over a GSM mobile modem. The device has a 128M read-only root file system, an MFS /tmp file-system (currently backed by hard-disk based swap), and a 64M /app read/write file system on hard-disk for storing transaction data. Transactions occur roughly 5->10 times a day. The application has been written to only append to files or to replace the file by creating a new file and then writing a single byte to redirect which file is in use. The problem is that in certain circumstances in power down (which can occur at any time), the /app file system is being corrupted beyond what an automatic fsck at boot can repair. Unfortunately it is not possible to mount and unmount the /app file-system around each write. My current kernel settings are: sysctl -w vfs.write_behind=0 kern.filedelay=2 kern.dirdelay=1 kern.metadelay=0 Can anyone please help with this write problem. I am also looking to move to compact flash in the next few months - how should the read/write file-system be mounted/options etc to work economically on the compact flash. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-small" in the body of the message
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