[1674] in linux-scsi channel archive
Re: SCSI or ftape?
daemon@ATHENA.MIT.EDU (Juergen Sauer)
Wed Apr 2 19:21:41 1997
To: submit-linux-dev-scsi@ratatosk.yggdrasil.com
From: jojo@sae.extern.fh-hannover.de (Juergen Sauer)
Date: 3 Apr 1997 01:46:10 +0200
Dave Wreski <tel1dvw@is.ups.com> schrieb
am Tue, 1 Apr 1997 00:28:29 -0500 (EST) in linux.dev.scsi:
DW> Hi all. I landed a little side job setting up a linux and NT network for
DW> a company near me. I'm now wondering what kind of backup solution I
DW> should offer. They will be backing up inventory data from a NT-based
DW> database. I'm not sure of the size of the data, but I don't think it will
DW> be more than 50 megs per day.
DW> I'm inclinded to sell them a 1542 and a DDS-2 4 gig backup drive, but that
DW> could cost near $1000.
DW> Should I get the scsi drive, or a simple 3.2 gig travan drive? What do I
DW> need to consider before making a decision?
There is only one possible solution: SCSI (QIC or DLT), if a rocksteady
backup is wanted.
If costs are important, you may be happy with a SCSI QIC drive,
those are avaible in 250 MB, 525 MB (antique) and upto 2,x GB.
The QIC525 drives are cheap nowadays.
A 4mm DDS2 DAT is a little more problematic in case of long term
uses, you have to ensure that the DAT drive is cleaned every 25th
tape change/backup cycle. 8 mm are a bit better (robuster).
I personally use DAT only for private and not vital backups.
The fantastic access times to backuped data makes it to a perfect
hot data swapout device, about 40s to access a mirgrated file is really
great.
But always use DATs with caution:
My first DDS2 drive reached the end-of-life after 2 years of dayly
operation and I couldn't restore from the latest written tapes, which
were written on the old/crashed drive with the new drive. This
happened to some customer of mine too, he didn't care about
cyclic cleaning of his drive ... and Murphies Law took the rest.
What is the worth of a useless backup ? NOTHING.
Our vital backup medium is a (slow) QIC525 tape drive from
Wangtek. About 7 years there was not one tape which lost any bit
of data - The archive tapes (elder than 5 years are still complete
funcional, some are elder than 10 years (QIC60 and QIC150)).
... and this drives (QIC 60, QIC 150) are _the_ standard tapes
in the unix world.
All SCSI tape drives report a Media sense key error if a problem
occour during backup sessions. This is very useful.
All floppy/tarvan streamers are not recommended because you
have to preformat the tapes, which takes a long time. I'm not
100% sure, but IMHO I think, it cannot be done during linux
operation (No format software).
>> The long term data security is not proven to me yet. <<
And I do not know, if the timing problem is solved with
this streamers, which made it nearly impossible to backup
during multitasking operation. What, if the host enters a
time of high cpu loads ? The data stream to the streamer
may be disturbed, the backup may be worthless.
This may be fixed with the newer tarvan drives.
I'm really interested in other statements of the long term
use of tarvan devices. If anybody knows -- please post your expieriences.
Data Backups are much to vital to me to collect my own
expierience. IMHP: In the case of data backup a responsable sysop
_has_ to be very conservative. The job depends on it!
A Backup medium is for data security and to buy the cheapest
solution is like a suicide on vital data for a company.
mfG
Jojo
-Schneckenpost-SlowMail-+--------Telefon-----+---eMails-FastMail----------
Jürgen Sauer Tel. +49 4209-3021 jojo@sae.extern.fh-hannver.de
Neue Str. 11 +49 172-4254411 jojo@linux.rz.fh-hannover.de
28790 Schwanewede/Germany FAX +49 4209 5217 CI$: 100013,1564
--
-Schneckenpost-SlowMail-+--------Telefon-----+---eMails-FastMail----------
Jürgen Sauer Tel. +49 4209-3021 jojo@sae.extern.fh-hannver.de
Neue Str. 11 +49 172-4254411 jojo@linux.rz.fh-hannover.de
28790 Schwanewede/Germany FAX +49 4209 5217 CI$: 100013,1564
