daemon@mcnc.org (David Daemon) (12/03/88)
I have received a good number of replies to my queries on the Exabyte
drive. First is a summary of what I gleaned from the responses to my
questions; second is the text of all the responses I have receieved
through 11/18/88.
Note--my summary is based on the responses and talking with sellers of the
device (*not* actual testing, since we don't have one (yet)).
-Brad
Summary:
1) What supplier did you order unit from and what guarantee and materials
(manuals, driver, etc.) did you receive?
Many resellers were mentioned (Helios, Artecon, Delta Microsystems,
Perfect Byte, Peripheral Devices, Unison). Most manuals sounded fairly
skimpy, but no real complaints. Warranties varied from 3 months to one
year depending on reseller. It appears that Sun OS 3.5, 4.0 and later
support the drive without problems; however, if you have an earlier
version of the OS, you need to be sure to get a driver from the reseller.
Also some dealers have their own seperate drivers.
2) what Unix utilities work with Exabyte?
All expected utilities seem to function from people's comments (tar, dd,
dump, restore, cpio, cat, etc.)
3) How is it error wise? I.e. 10^13 seems a little on the low side to me.
(Especially compared to the VHS Gigastore on our Vax which quotes it's
error rate at 10^23).
Well, 10^23 is overkill, and 10^13 should be fine. 10^13 means you can go
through 5000 tapes at 2 Gigabytes a piece (probably longer than you'll
have your job :-)). I was looking for 'actual use' responses here; no one
had any complaints.
4) How much do you find you can actually store on 1 tape; and how does
this relate to the number of files on the tape. E.g. on other helical
scan devices (like the Gigastore) large amounts of potential storage space
is wasted between seperate files on the tape.
What I'm looking for here is how much data space is wasted between file
marks on the tape (this tends to be larger on helical scan devices than
regular 1/2" magnetic tape). The two responses I got indicated the loss
was 2Mbytes; thus this is something to consider if you wanted to write
many small files (e.g. 1000 files won't fit on a 2 Gigabyte cartridge
regardless of filesize if you write them all out as seperate files). Most
people weren't concerned with this as their major use for the Exabyte was
for dumps. We use our Gigastore (and plan to use the Exabyte) for
additional purposes, such as storing large datasets of medical images.
Rather than write each image out seperately, we do various things to
concatenate data into larger lumps in order to cut down on the storage
losses between files.
My additional $0.02 for those of you who don't have Exabyte or similiar
capability helical scan drives:
1) It's use in doing backups alone justifies such a device--almost
universally everyone backups up their computer (or computer systems
on network) every night, automatically.
2) You will soon find additional uses for it's storage capacity.
[[ The texts of many of the responses were included with this summary.
They have been placed in the archives under "sun-spots" as
"Exabyte.replies". The file is 14337 bytes long. It can be retrieved via
anonymous FTP from the host "titan.rice.edu" or via the archive server.
For more information about the archive server, send a mail message
containing the word "help" to the address "archive-server@rice.edu".
--wnl ]]