****Original question*******
I am thinking of moving from magnetic media to CDRs for data archival. I
just reviewed some earlier AMMRL discussion on this and it seems to be the
best solution for me. One query for the group:
Is a CD created by a CD-R drive on a PC (compliant with ISO 9660) readable
on the CD drives of other platforms such as SUN and SGI?
Please post any replies to me and I will summarize.
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I have successfully written ISO-9660 CDs that can (sort-of) be read
directly on the Sun; however, ISO-9660 will only support the "8.3" (DOS)
filename format. This is a mess with UNIX filenames.
The best solution for us is to use NFS to connect our NT-server systems to
our UNIX filesystems. Then, you can share filesystems transparently both
ways. Using either GEAR or the Adaptec EZ-CD-Writer software, you can
write CDs on the PC with long (256 character) filenames. We can directly
share the CD-ROM drive itself over NFS (export to the UNIX box), or drag
and drop the file(s) form the CD to the UNIX filesystem at the NT-machine.
This works _really_ slick, and it's almost like the CD-ROM drive in every
PC is directly attached to the Suns.
We use Xlink's Omni-NFS/X package, which gives full NFS support, runs under
Windows 95 _and_ NT, and it gives Windows-95 computers the ability to print
directly to TCP/IP print servers usint LPD protocol (already built-in to
NT). It also has a nice X-terminal that lets you run X-windows
applications on remote UNIX boxes.
It's pretty affordable for us educational types as well...like under $150
per seat, or something like that.
**************************
We just installed a CD-R (Ricoh 2x6 external CD-R, Cd-R/W) on our Sun Ultra
1 140 and it works great. CD's created are ISO 9660 compliant and I am
able to read these with my PC. I know you're interested in CD's recorded
with a PC, but thought this information would be useful.
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We have created ISO formatted CD using both PC and SGI. Both are
readable on the other platform. Almost all of our current CD creation
for NMR data is now being done on SGI because that eliminates one file
transfer.
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I know it's true the other direction. I have made CDRs on an SGI
and can read these on a PC; it should work both ways.
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I routinely back up user data for an SGI by writing ISO9660 disks with a
powermac after transfering the data to my mac over the net. Those disks are
readable on Suns, SGIs and PCs at least. At one time PCs had a lot of
trouble writing CDR but I think that most of the glitches have been fixed
by a combination of better drivers and better firmware on the boxes. Can't
insure it, as I don't speak MSDOS.
**************************
We have just started using a CD-R in our lab. My original intention was
to connect it to either an SGI or linux box and use "cdrecord"
http://www.fokus.gmd.de/nthp/employees/schilling/cdrecord.html
As it turned out all of our SGI's already have too many SCSI devices (not
that many...but too many for the flakey SCSI controller) and I haven't
gotten around to ordering a SCSI card for my linux box. So, I ended up
hanging on our new G3-Power Mac using the Adaptec "Toast" software. This
actually works quite well, but some thought needs to be given to backup
strategy: this is probably true no matter which platform is used to
operate the CD-recorder. The ISO-9660 format discs that I have written do
seem to be readable on everything that I have tested. There are file name
limitations, however, and MSDOS/Windows represents the lowest common
denominator with the most restrictive files names. I am told (but haven't
found it in writing) that ISO-9660 allows 32-byte filenames and 4-deep
directory hierarchies. DOS, of course, is limited to xxxxyyyy.zzz format
file names, no case sensitivity. The default behavior of Toast and
CD-Record when making ISO-9660 discs seems to be to shorten filenames to
make them DOS-compatible. On the Mac version of Toast, there is a flag
to allow Mac-compatible file names. This also permits long (up to
32-character) Unix/case-sensitive filenames.
Another issue is the preservation/loss of date/time/ownership/permission
information when writting individual files.
My recommendation is to create "tar" or "zip" archives with short names
that are containers for complex directory structures. This also
preserves date/ownership/permission information for the files inside the
archive. Many tar or zip files can be written to the CD in one session.
"Fetch" on the Mac, in binary mode, is useful for retrieving tar files
or even limited directory structures. Stay away from the mac version
of NCSA telnet for reliable FTP file transfers.
"Multi-session" discs seem to work OK. In this mode, the disc is not
finalized, so additional writings can be made to the CD in later sessions.
Supposedly, some older CD-drives might have a problem with the later
tracks, but I have not experienced this problem. Also, it is said that
a file written in a 2nd session with the same name as one in the first
session will veil the presence of the first.
Writing audio discs seens to work quite well. We just bought one to
use at home for my son's recording project. Let me tell you about......
Re-writeable CD's are an interesting idea, but the media is expensive
and the discs are often not readable in conventional CD drives.
Regular CD-R blanks are quite cheap $1.65 each in lots of 25
I just bought some Kodak/no-silkscreen/with jewel case from TecBridge
Data products 1-800-972-7405. TecBridge, although in New Hampshire,
gives great service: overnight shipping is about $5.00
I would recommend the 4x-record drives such as the Yamaha
Yamaha CDR-400 series which have 2MB buffers or the Panasonic CW-7502,
which has a 1MB buffer. The larger buffers help prevent data underflow
problems which will cause a writing session to bomb.
The general wisdom is that files to be written should be on a local
hard drive of a system that is not too busy. So, once again, "strategy"
would include providing a scratch area on a hard disk connected to the
same computer as the CD-recorder to use for assembling the files to be
recorded.
In summary: CD-R's are great, Micro-$oft $ucks, SGI is SGI, Mac's work
surprisingly well (sometimes) and Linux rules!
*************************
Regarding CD-R's, the media is readable in any cdrom drive, or should
be readable. Audio formatted CD-Rs will play in Audio CD players.
This is because the change in reflectivity representing zeros and ones
is large enough for cd and cdrom players to detect.
This is not generally true for CD-RW. Here the reflectivity changes by
a much smaller percentage, and is not readable by any older drives,
although some new (last 6 mos) drives are supposedly able to read
CD-RWs.
None of this addresses files and file sytem formats.
ISO9660 is a file system format, and is readable/mountable by most or
all operating systems. Using this format may require 'PREMASTERING' your
data, that is, creating an image of the CD-R to be made on a
hard disk partition first, then burning the disk. Also, when burning a
disk, your computer should probably not be doing much else(highly
dependant on your system and configuration). An 'UNDERFLOW' of data to
the cdrom drive could cause an error and a wasted disk.
There are other formats (multisession, etc.) but I am not familiar with
the quirks and requirements of using these formats.
****************************
We have recently made the same sort of move, and the answer to your
question seems to be no. Basically ISO9660 is readable by PC's. Many
of the software packages available have extensions which will support
long file names under Windows95 ot NT4.0, but there may still be some
incompatibility/renaming if you are copying from Unix to a PC
(underscores, dots, mixed case, etc may be converted - Uncle Bill knows
best!). The CD's we have produced (using Adaptec CD writing software)
are readable on a standard PC CD reader under Windows95 / NT4.0, but not
on a Sun CD reader. (Interestingly, they are readable on a PC running
Linux!) After some searching around the web I discovered that to make
the CD's readable on standard Unix boxes you need to write the file
system with something called Rockridge extensions. You can get this as
commercial software for PC from hycd (
http://www.cdr1.com/html/hycd_data.html ), but they seem to have stopped
providing the low-cost (data only) package they used to sell and now
only sell a full CD publishing package for about 500 Dollars (at least
that's the story I got from their European distributors). I think there
may also be suitable packages available for Linux (free) but I have no
experience of these.
Other sites which I found useful while looking into this were
http://www2.osta.org/osta/html/cdr2.html and http://www.cd-info.com/
I hope this is useful to you. If you find further information about
making CD's readable on Unix box's I would greatly appreciate it if you
could share it.
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Well, I am also considering CD-R as a data storage medium but have not
yet made a purchase. In short, yes using the ISO-9660 standard (level
1) the CD's that you create will be readable on other platforms (DOS,
UNIX) provided that you name the files in a 8.3 format like in DOS.
There are also levels 2 and 3 in the ISO-9660 standard that support
longer names (UNIX, Win95/NT, Mac). See the following web sites for
more info on CD-R and the ISO-9660 standard:
http://www.fadden.com/cdrfaq
http://www.adaptec.com/tools/compatibility/cdrecfilename.html
Also, there was a review of CD-R and CD-RW drives in a recent issue of
PC Magazine (March 10, 1998 pp 151-184). This article can also be
accessed via the web:
http://www.zdnet.com/pcmag/features/cd-rw/index.html
*****************************
we have an HP Surewriter and the files it generates on cd disks are
readable by SGI computers.
****************************
We routinely archive to CD-R using ISO9660 format; the resultant discs can
be read with Unix, Mac and PC systems. We actually write the discs on a
Mac because of the iniquitous cost of Unix CD writer software.
***************************
We have just tested this scheme out for old Bruker data and found that when
we write to CD (from an NT-PC) we can read the data under Windows 3.1 but,
more importantly, we can also read the data on our SGI O2. Hope this is
useful.
****************************
I believe that any CD created using an ISO 9660 compliant file system should
be compatible on nearly all platforms. I've had success using ISO
9660-compliant cd's with PC, Unix, and Mac machines. I assume that this
would work for SUN and SGI as well.
**************************
This is how I'm archiving for SGI.
Check filenames (and other little parameters)
- I've been using Toast software (on a Mac)
and unless you set parameters just right, filenames can get truncated
and/or sense of upper/lowercase gets lost.
Also,the dye on the CDR is important - for a while some manufacturers used
a dye
which, while archival, cannot be read by CD-ROM drives with lower power
lasers.
I believe that the dye can be identified by its gold color (visible
on the read/write side of the disk (not the label side).
***************************
I have made ISO 9660 compliant disks on Macs, and they work on Suns. Other
combinations I have not tried, but my guess is they will work.
************************
We have had a CD recorder on an old (and sad to say slow)
PC for a while now and have written UNIX compatible CDs
with software from HyCD. As I recall this meant
we could have a deeper directory tree. There was a reason
for not staying with ISO9660. WE have read these
CDs on SGIs and also on our SUN without difficulty.
Well there is a problem with multisession CDs but
we generally have so much stuff that we just write
once and forget about it.
********************************
Jeff de Ropp
NMR Facility, UC Davis
jsderopp@ucdavis.edu
530-752-7677
530-752-8109 Fax
NMR Facility Web site URL http://www.nmr.ucdavis.edu