glee@athena.mit.edu (Gilbert Huppert) (01/08/91)
I have a few questions which came up last night when I was installing a new Wren-7 drive from Seagate (1200 Mb). I know that the formatted capacity should be 1039+ Mb, and this is what the partition table claims is available. However, when I run newfs.ffs to set up the disk header, I find that I have only 985+ Mb. There is also the problem that the system automatically saves 10% of the diskspace for file overruns to try to minimize crashes due to out of disk space for open files. While this may be all right for small disks, I really have no need to save 98 Mb for this purpose since this disk is only being used as remote file space for PC's. Question #1: How do I access the full potential of the disk? Question #2: Is there anyway the minimize the reserved disk overhead? At the same time, I rearranged some of my filesystems into a more logical order in order to remove conflicts when one filesystem is not already mounted. This left me with one partition of one disk (sdc0d0s7) on an RC2030 which will not mount. I always receive the "Device or resource busy" message. I know that the partition is not mounted anywhere, and the directory I am trying to mount is not busy. This leads to : Question #3: Any ideas why I might not be able to mount a free filesystem? Replies are greatly appreciated. Gil Huppert P.S. I am currently running OS4.01 and OS4.10 on my machines since I have not received all the update tapes. To install the 1.2 Gb drive I used a 4.51 miniroot since 4.01 does not recognize this drive.
rogerk@MIPS.com (Roger B.A. Klorese) (01/08/91)
In article <1991Jan7.160027.5883@athena.mit.edu> glee@athena.mit.edu (Gilbert Huppert) writes: >Question #1: How do I access the full potential of the disk? Well, it's not clear what the full capacity really is, Gil. When disk marketeers talk about megabytes, they talk about thousand-bytes, not 1024-bytes, so there's a loss right there. Additionally, the FFS structure, inode table, superblocks, etc. do eat a good bit of space. >Question #2: Is there anyway the minimize the reserved disk overhead? Actually, the 10% is not reserved to minimize crashes, but because the cylinder-block allocation algorithm gets messy on very full disks. You can tune the threshhold for a partition down from 10% with /etc/tunefs.ffs: /etc/tunefs.ffs -m 3 /dev/rdsk/isc0d1s2 would drop it to 3%. (You would need to do this on an unmounted filesystem, or tune, unmount, and remount, for it to be seen.) >Question #3: Any ideas why I might not be able to mount a free filesystem? Be certain that no partitions in use overlap your problem partition. -- ROGER B.A. KLORESE MIPS Computer Systems, Inc. MS 6-05 930 DeGuigne Dr. Sunnyvale, CA 94086 +1 408 524-7421 rogerk@mips.COM {ames,decwrl,pyramid}!mips!rogerk "I'm the NLA" "The problem with the rat race is even if you win you're still a rat." - Tomlin
jeff@u02.svl.cdc.com (Jeff Needham) (01/09/91)
glee@athena.mit.edu (Gilbert Huppert) writes: >I have a few questions which came up last night when I was installing >a new Wren-7 drive from Seagate (1200 Mb). I know that the formatted >capacity should be 1039+ Mb, and this is what the partition table claims >is available. However, when I run newfs.ffs to set up the disk header, >I find that I have only 985+ Mb. Everytime I format a Wren VII, I also get this number. I know someone who knows where the space goes and will get back to this. >At the same time, I rearranged some of my filesystems into a more logical >order in order to remove conflicts when one filesystem is not already >mounted. This left me with one partition of one disk (sdc0d0s7) on an Partition 7 is often used a a swap device and may be mounted by the kernel "%/etc/swap -l" will give you this information. jeff -- Disclaimer - Waiting for the Oracle port to the 6600 | Jeff Needham | Oracle Performance Group | Control Data - Santa Clara, CA - INTERNET jjn@hare.udev.cdc.com
kdenning@pcserver2.naitc.com (Karl Denninger) (01/11/91)
In article <439@spim.mips.COM> rogerk@MIPS.com (Roger B.A. Klorese) writes: >In article <1991Jan7.160027.5883@athena.mit.edu> glee@athena.mit.edu (Gilbert Huppert) writes: >>Question #1: How do I access the full potential of the disk? > >Well, it's not clear what the full capacity really is, Gil. When disk >marketeers talk about megabytes, they talk about thousand-bytes, not >1024-bytes, so there's a loss right there. Additionally, the FFS structure, >inode table, superblocks, etc. do eat a good bit of space. Yep. I have found that about 10% of the disk area is eaten internally on ffs partitions. This is true across systems; Suns do this too. However, I'm happy to pay the price for the better performance and things like long filenames -- two things I can't have on System V filesystems from anyone... even those vendors that do support it. I'll take the ffs anyday. >>Question #2: Is there anyway the minimize the reserved disk overhead? > >Actually, the 10% is not reserved to minimize crashes, but because the >cylinder-block allocation algorithm gets messy on very full disks. You >can tune the threshhold for a partition down from 10% with /etc/tunefs.ffs: > > /etc/tunefs.ffs -m 3 /dev/rdsk/isc0d1s2 > >would drop it to 3%. (You would need to do this on an unmounted filesystem, >or tune, unmount, and remount, for it to be seen.) Be careful doing that however -- it MAY cause somewhat serious performance problems when the disk gets nearly full! >>Question #3: Any ideas why I might not be able to mount a free filesystem? > >Be certain that no partitions in use overlap your problem partition. That will certainly cause problems :-) One other thing I have noticed: Unsupported disks are no problem at all on the MIPS systems. You just have to do some strange things in the standalone formatter, and make the filesystems by hand (ie: use mkfs.ffs, not newfs.ffs). The basic trick is to enter all the information (cylinders, heads/cylinder, etc) -- the low level format is unnecessary, as is the bad-block scan (assuming you know that the drive has correctly spared the bad blocks internally). The scan isn't a bad idea to run if you have any questions.... I have no idea if this would work for bootable system disks, but I can't see why not if you follow all the other (necessary) rules about partition layout and the like. I have done two drives with this method, and find that I get both excellent performance AND allocation the way I want it, when I want it. Neither one is "officially" supported (Maxtor 8760Ss) however they work real well. One trick -- specify a few (20 or so) blocks less than the actual partition size when you do the "mkfs.ffs". For some reason unknown to me, if I specify the exact block count the system refuses to initialize the partition.... even though there IS enough space on the volume in the partition where I'm trying to put the new filesystem. It complains about not being able to write the last couple of blocks and quits.... Also, being truthful (ie: supplying the information) about sectors/track and the like seems to help I/O performance somewhat. One final warning -- in the 3260 cabinets, they warn you to jumper secondary and beyond drives to power up on a START command. Most SCSI devices don't ship in this configuration; check the jumpers before you install! I have no idea how serious this problem really is, but 'tis better to be nice to the power supply :-) Enjoy! 700MB disks currently run about $2k each, 1.2GB drives are a little more. Quite reasonable overall... -- Karl Denninger - AC Nielsen, Bannockburn IL (708) 317-3285 kdenning@nis.naitc.com "The most dangerous command on any computer is the carriage return." Disclaimer: The opinions here are solely mine and may or may not reflect those of the company.