Linux on PE2950, PV220S and very slow PV124T

David B. haazeloud at
Wed Sep 3 02:12:52 CDT 2008

> 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.
Hi John,

I'll have a look to this soon (iostat and make tar before write a tape).
Thank you.

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