Date: Fri, 22 Aug 1997 02:50:42 +0200 (CEST) From: root@deadline.snafu.de (Andreas S. Wetzel) To: andrew@zeta.org.au (Andrew Reilly) Cc: scsi@freebsd.org Subject: Re: newfs on Fujitsu R640 (2k sector media) Message-ID: <m0x1hw2-000Bn9C@deadline.snafu.de> In-Reply-To: <199708212326.JAA26191@gurney.reilly.home> from Andrew Reilly at "Aug 22, 97 09:25:58 am"
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Hi!
---
Andrew Reilly writes:
] On 21 Aug, Andreas S. Wetzel wrote:
] > I just got my new Fujitsu 2513A6 drive with a 640 Mb media and had it
] > running in less than an hour, using FreeBSD 3.0-current SMP as of 08/15/97.
]
] Bruce Evans has also suggested that 3.0-current would be needed. Good
] to hear that it works, though. Incidentally, what is the significance
] of the 6 after the 2513A model number? I don't think my drive had one
] of those.
AFAIK the 6 indicates that the drive has a 2 Mb cache. Drives with a
2 have 512k I think. Although I cannot say much about the cache, since
I have not enabled it yet on the drive. The default setting is to disable
the cache. Will check this real soon :-)
] >> I'm using this disktab entry, which I built out of the
] >> numbers reported at boot time, but it's essentially the same
] >> as the one that you get with disklabel -w -r auto:
] >>
] >> fuj640|R640|Fujitsu R640 media Meg 3.5inch Magneto-Optical:\
] >> :ty=removeable:dt=SCSI:rm#3600:\
] >> :se#2048:nt#64:ns#32:nc#151:sc#2048:su#310352:\
] >> :pa#310352:oa#0:ba#16384:fa#2048:ta=4.2BSD:\
] >> :pc#310352:oc#0:
] >
] > Obviously this disklabel is missing at least the number of tracks per
] > cylinder (nt#XXX).
]
] No it isn't, nt# is on the third line, just after se#. The geometry is
] obviously ficticious, but I went with this (which was reported by the
] drive) because I read that the number of cylinders affected the number
] of super-block copies, and I didn't want to waste too much space on
] those. The capacity works out the same. Did I err?
Sure the capacity is in all cases 310352 x 2048 byte sectors.
I think the number of super block backups is dependent from the number
of cylinders per cylinder group. This is an option you can supply to the
newfs command, so I think it isn't that important in the disklabel.
But the maximum number of cylinders per group is affected by the blocksize
and possibly some other parameters. Not quite sure about this, I used to
choose the maximum value that newfs will suggest. A look at a similar disktab
entry for a sony drive (should be contained in /usr/src/etc/etc.i386/disktab
in 3.0-current) does also have nt#1, although the number of sectors seems
to be different for this drive/entry, and hence, the drive does only
physically use one surface :-)
] > [...]
] >
] > # disklabel -w -r od0 MO640
] > # newfs -m 0 -o space -i 12288 -u 16 -t 1 -c 413 /dev/rod0a
] > /dev/rod0a: 1241408 sectors in 19397 cylinders of 1 tracks, 64 sectors
] > 606.2MB in 47 cyl groups (413 c/g, 12.91MB/g, 1088 i/g)
] > super-block backups (for fsck -b #) at:
] > 32, 26464, 52896, 79328, 105760, 132192, 158624, 185056, 211488, 237920,
] > 264352, 290784, 317216, 343648, 370080, 396512, 422944, 449376, 475808,
] > 502240, 528672, 555104, 581536, 607968, 634400, 660832, 687264, 713696,
] > 740128, 766560, 792992, 819424, 845856, 872288, 898720, 925152, 951584,
] > 978016, 1004448, 1030880, 1057312, 1083744, 1110176, 1136608, 1163040,
] > 1189472, 1215904,
]
] Many super-block backups. Are they nececssary? What is the
] significance of having so many? Do meta-data operations have to update
] all of them?
I'm not quite sure if there is a real need for so much superblock backups,
and I haven't been involved in filesystem tuning that much until now.
I try to keep the number low by having as much cylinders per group as
newfs permits, in this case it computed it to be 413 and I think 47
super-block backups is not that much for a 640 Mb media.
] > # mount /dev/od0a /mnt
] > # df -i
] > Filesystem 1K-blocks Used Avail Capacity iused ifree %iused Mount
] > /dev/od0a 613730 2 613728 0% 1 51133 0% /mnt
]
] Lovely to behold.
Yes indeed.
BTW: Did you manage to boot off your MO-drive?
Regards, Mickey
--
(__)
(@@) Andreas S. Wetzel Mail: mickey@deadline.snafu.de
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