Scenario:
I have a machine with a bunch of 18G disks and one raid5 arrray of 420G [1]
I have hooked up an LTO ultrium tapedrive to that machine
(100G uncompressed, 30Mbit/s transfer rate (that's 10G per hour
uncompressed))
if I ufsdump [2] the raid array to that LTO drive, I get indeed almost 10G
per hour.
I was using amanda, with some space on that disk allocated as holding
space. And I was getting arund 6-7000 kps Xfer rate.
since all disks were local to my machine, I changed amanda.conf to have
- only 1 dumper
- not use any holding space
The next amanda run took over 18 hours to complete (a Xfer rate of less
than 1G per hour (350 - 400 kps)
Now I switched it back to
- multiple dumpers
- use holding disk (accept for the RAID array itself)
and it looks im getting 6 - 7000 kps again.
Can anyone explain this to me ?
I was expecting that since all disks are local disks, I would be getting
roughly the same results in both setups.
[1] raid 5 and 1 hotspare, disks hotswappable .. had one disk die in there,
replaced it whitout having to shut down the machine or the diskpack ..
[2] Yup, Im using solaris (2.6 and up )
On a related note:
I was trying to use gnutar iso ufsdump to backup the raidarray , so that I
could use exclude files , and the tar estimate takes easily over an hour ,
the ufsdump based estimates are done much sooner (30-ish minutes).
Any clue ;)
Kind regards,
--
Gerhard den Hollander Phone +31-10.280.1515
Technical Support Jason Geosystems BV Fax +31-10.280.1511
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