From: [log in to unmask] on 08/24/98 07:41 AM
Please respond to [log in to unmask]
To: [log in to unmask]
cc: (bcc: Lee Gunter/BCBSO/TBG)
Subject: Re[2]: Re[2]: DDS-3 vs. DLT? Reliability?
>I look forward to seeing the results of your survey. It would be useful
>to include some real life backup timings on DDS vs DLT.
We've got a couple of lurkers, er customers out there that use DLT - it's
up to them whether or not they want to publish their results. I know of
a couple that are pretty darn impressive, but I'll have to let them decide
whether or not to speak up.
Regards,
M.
After Mark's "gentle" prod, I'm including the statistics from our last
"full" system backup.
We exclude a very large account, but the file space is still significant.
You'll note, too, that
the compression percentage is stated as 35% ... we specify a low (2:1)
software compression value and
leave compression enabled on the DLT's (on Orbit's advice), so the final
compression percentage
is more likely closer to 70%. The backup uses three (3) DLT's in parallel
- each on a dedicated
SCSI-2 channel.
To cut to the chase, 124.8 GB is stored in 4.5 hours -- approximately a
27.7 GB/hour rate. When
we used a high software compression factor and no drive compression, the
throughput rate was
approximately 31 GB/hour.
Lee Gunter [log in to unmask]
**************************************************************************
* Tape statistics for volume # 1 Volumeset: Volume: *
* compression percentage: 33 % Backup : # 1 Name: *
**************************************************************************
* total number of tape errors : 0 backup ldev number: 97 *
* total number of tape retries: 0 *
* total number of data blocks 918095 ( 116598065 sectors,28466.3 Mbytes) *
* time: beginning: 20:09:37, ending: 00:43:33, elapsed: 04:33:56 *
* amount of disk space stored: 174513465 sectors (1645.8 megabyte(s)) *
**************************************************************************
**************************************************************************
* Tape statistics for volume # 2 Volumeset: Volume: *
* compression percentage: 36 % Backup : # 1 Name: *
**************************************************************************
* total number of tape errors : 0 backup ldev number: 98 *
* total number of tape retries: 0 *
* total number of data blocks 872410 ( 110796070 sectors,27049.8 Mbytes) *
* time: beginning: 20:09:53, ending: 00:43:33, elapsed: 04:33:40 *
* amount of disk space stored: 174513912 sectors (1645.9 megabyte(s)) *
**************************************************************************
**************************************************************************
* Tape statistics for volume # 3 Volumeset: Volume: *
* compression percentage: 35 % Backup : # 1 Name: *
**************************************************************************
* total number of tape errors : 0 backup ldev number: 99 *
* total number of tape retries: 0 *
* total number of data blocks 883535 ( 112208945 sectors,27394.8 Mbytes) *
* time: beginning: 20:10:10, ending: 00:43:33, elapsed: 04:33:23 *
* amount of disk space stored: 174513898 sectors (1645.9 megabyte(s)) *
**************************************************************************
.
.
.
FILES STORED: 19323
FILES NOT STORED: 18
total number of blocks: 2674040 (339603080 sectors, 82910.9 megabyte(s))
number of blocks on first volume: 918095 (116598065 sectors, 28466.3
megabyte(s))
compression percentage: 35 %
required size of filebuffer: 223005015 sectors (54444.6 megabyte(s))
total amount of disk space stored: 523361568 sectors (127773.8
megabyte(s))
total number of tape errors: 0 + 0 errors in store directory
total number of tape retries: 0 + 0 retries in store directory
This store took 275 minutes, 12 seconds
************************************************************************
* # of files * size (Ksectors/Mb) * file type *
************************************************************************
* 2030 * 2264.69 / 552.90 * program files *
* 1243 * 363162.09 / 88662.63 * IMAGE database files *
* 122 * 15650.86 / 3821.01 * KSAM files *
* 59 * 30.74 / 7.50 * VPLUS files *
* 1259 * 441.44 / 107.77 * SPOOL files *
* 12490 * 124162.34 / 30313.07 * ASCII files *
* 6833 * 399199.22 / 97460.75 * BINARY files *
* 781 * 19.78 / 4.83 * Byte stream files *
* 154 * 2.46 / 0.60 * Symbolic links *
* 1 * 0 / 0 * Device links *
* * * *
* 14942 * 103306.05 / 25221.20 * not modified in past 7 days *
* 12921 * 72620.14 / 17729.53 * not modified in past 30 days *
* 9427 * 35001.86 / 8545.38 * not modified in past 6 months *
* 8043 * 18851.07 / 4602.31 * not modified in past 1 year *
************************************************************************
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