inodes, partitions, and Re: Advise about Wren 7 SCSI disk.

[Bruce R. Larson]

>In article <1991Jan24.194219.6604 at world.std.com> steveo at world.std.com (Steven W Orr) writes:
>>I am about to decide to buy a 1.2G Seagate Wren 7 SCSI drive.
>>
>>The question has been raised that I might not be able to take advantage
>>of the space on the disk because each physical device has a limited
>>number of inodes.
>

Here are my two cents worth.

In SysV/386, up to Rel 3.2.2 at least, the following are true:
*)  there are a maximum of 65,536 inodes per filesystem or division

*)  there are generally five (5) device names, as Ed Hew mentioned,
    available for partitions to be associated with filesystems.
    [NOTE: Ed also mentioned that if you have a SCSI hard disk, then
     it may be possible to reclaim SCO's `recover' area for use as an
     additional filesystem, however I'd try it myself before
     recommending it to a client.  In any event, if you succeed
     you will have six filesystems instead of five.]

*)  the default ratio of 512-byte blocks per inode for the mkfs
    command is eight (8), and news filesystems are usually made with
    four blocks per inode (because news consists of lots of small files).

This summarizes to a max of 1.28GB on a single disk with five 256MB
filesystems created using mkfs' default blocks:inodes ratio.  Since a
1.2GB disk should format down to to about 980MB or so, it is certainly
possible to cover the disk with five filesystems, even if one is a
128MB partition for news, but that doesn't mean it is wise to do so.

I prefer to configure a disk with a filesystem structure that promotes
good performance and easy maintenance, so a 1.2GB disk would be
impractical for me.  I'm too accustomed to the luxury of separated
root, tmp. usr, u and usr2 filesystems to compromise their existence
for the sake of getting a monster capacity hard disk.  I'd rather have
two merely huge disks, like the Wren VI FH or the soon-to-be-released
12ms 24mz Wren Runner II (a real smoker, this one), and enjoy the benifits
of increased capacity and performance while maintaining the safety of
separated fileystems.

However, if someone gave me a 1.2GB disk, here is how I would probably
slice it up (add salt to taste):
* small root filesystem (/)      35MB to  75MB
* swap space                     15MB to  80MB
* usr filesystem                150MB to 256MB
* src filesystem                         256MB
* news filesystem                        128MB (4 blocks per inode)
* u filesystem                        the rest

I decided to post this instead of mailing to Steve (or calling him)
because this seemed to be of general enough interest.

Bruce 

Bruce R. Larson				   | 
Integral Resources, Milton MA		   |
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