On Thu, Mar 03, 2011 at 02:13:00PM +0100, Gour wrote:
> Hello,
>
> after performing testing of my HP Ultrium 448 drive with:
>
> amtapetype -f /dev/nst0
>
> I got the following result:
>
> Checking for FSF_AFTER_FILEMARK requirement
> Applying heuristic check for compression.
> Wrote random (uncompressible) data at 21864712.2580645 bytes/sec
> Wrote fixed (compressible) data at 50207857.7777778 bytes/sec
> Compression: enabled
> Writing one file to fill the volume.
> Wrote 203994431488 bytes at 22522 kb/sec
> Got LEOM indication, so drive and kernel together support LEOM
> Writing smaller files (2039939072 bytes) to determine filemark.
> define tapetype unknown-tapetype {
> comment "Created by amtapetype; compression enabled"
> length 199213312 kbytes
> filemark 207 kbytes
> speed 22522 kps
> blocksize 32 kbytes
> }
> # for this drive and kernel, LEOM is supported; add
> # device-property "LEOM" "TRUE"
> # for this device.
>
>
> However, when comparing the above result with the entries at
> http://wiki.zmanda.com/index.php/Tapetype_definitions#Hewlett-Packard_Ultrium_448
> I see that all of 'em have: "filemark 0 kybtes", while I got "filemark
> 207 kbytes"
>
> What do you think, iow. shall I use the one arrived after amtapetype
> testing?
207KB for each filemark?
Wow, what a huge waste!!
But consider the difference from a 0KB filemark to Amanda's
calculations. If it were to write 1000 separate tape files,
"wasting" 207MB in filemarks, its calculations of how much
dump data it could fit on the tape would differ by 0.1%.
--
Jon H. LaBadie [email protected]
JG Computing
12027 Creekbend Drive (703) 787-0884
Reston, VA 20194 (703) 787-0922 (fax)
