sysstat 1
in the last few columns you will see tape I/O (read and write columns) in KB/sec
Remember, if you have "wide" directories with lots of small files, your tape I/O
will only be as fast as the filer can get them off disk.
I have an R200, depending on the data I get 13-17MB/sec for about 30-40 million files.
(literally hundreds of thousands of entries per directory with many directories) over 3-5TB
all the way to 60-80 MB/sec for directories with large files (usually thousands to low millions of files
over 2-3 TB)
This is to local attached LTO-3 (via FCAL).
I used to have AIT-3 that topped out at 15MB/sec with compression. (really slow for the multi-TB dumps)
--tmac
On 10/18/07, John Foley <johnf@comm.mot.com> wrote:
filer gurus --
got a question about tape drive performance, when directly attached
to the filer (via SCSI).
We have an F825 (soon to upgraded, we hope !) to which we've attached
both an LTO-2 and LTO-3 8-tape library unit (these are from Dell, just
FYI). The LTO-3 is a recent acquisition, and so we thought we'd run a
few tests, to confirm that the LTO-3 drive is "faster". Well, it
isn't - at least doesn't appear to be, based on an overnight full
backup of the filer.
Now, I know there are a lot of things to watch out for when making
tests like this, but I though I'd check with the group here to see
if anyone knows...
- is there a way to tell what the data rate to the tape drive is
from the filer, over the SCSI bus ? I'm looking for more of an
instantaneous measurement, rather than the overall average of
(amount of data moved / time it took).
- anyone else played around with this (ie, attempting to measure the
data throughput from filer to SCSI attached tape drive) ? If so,
what did you try, and what conclusions did you reach ?
Thanks much for your replies and time !
John
--
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John Foley < johnf@comm.mot.com >
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--
--tmac
RedHat Certified Engineer #804006984323821