Linux on PE2950, PV220S and very slow PV124T

John LLOYD jal at mdacorporation.com
Tue Sep 2 11:37:38 CDT 2008


> Transfert from memory to PV124T is ok
> Transfert from internal disks to PV124T is ok.
> Transfert from PV220S VD2 (big files) : 3 hours for 350 GB, ok.
> Transfert from PV220S VD1 (lots of small files) : 20 to 22 
> hours for 300 
> GB, NOT ok.
> (around 12 000 000 files)

Regarding the file count and size, you are not going to make a direct
backup to tape work, in my opinion.

Each file requires, on average, a disk seek, and each file is only 25
kbytes.  Your disks can only do 100 seeks per second, and even assuming
all 8 disks can seek at once that is only 100 * 8 * 25k = 20 MB per
second.  Your LTO-3 drive cannot operate this slowly.  You can confirm
this with "iostat -x" when running a backup -- the last column will show
100% busy but only a few megabytes/sec throughput.

I would suggest creating tar files, of some reasonable size, perhaps
based on your knowledge of the directory structure of your 12M files,
and back those up. A few large tarfiles will work, based on your
experience with VD2.   You might need additional disk space to be able
to do a "full" backup of VD1.


--John




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