I understand that I am running the lto3 on the slow side and it could
damage my tapes , and possibly the drive. Since I can write at 55mb a
sec when no reads are occuring I should be able to tweak my config to
only write to tape when I have a full holding disk. But I haven't been
able to do this yet. It seems I can fill the holing disk once then
after it writes everything to tape it starts streaming writes over the
network.
Another option is to get a larger faster holding disk , but that costs
money.
I like to see more example configs with setups similar to mine.
Sent from my iPhone
On Dec 8, 2009, at 5:15 PM, Joshua Baker-LePain <jl...@duke.edu> wrote:
On Tue, 8 Dec 2009 at 5:02pm, ckotil wrote
With my LTO3 drive, and 2x500GB sata 7200rpm drives in raid1. When
I write from disk to tape I can hit 55MB/sec max. However my dumps
are often much larger than the holding disk. I am forced to stream
data to the tape drive which slows the write.
Typical write to tape speed for a dump averages 20MB/sec. When
writing to tape I can dump 100GB in roughly 1 hr and 45 min. Im
sure with a proper config I could make my dumps more efficient. In
the amanda.conf, tape type is accurate. I think the flush-threshold
settings could use some tweaking to better utilize the limited
holding disk.
LTO3's native speed is 80MB/s. AFAIK, it can only throttle down to
half that. Any slower than that and you are shoe-shining your
drive, which is bad for your tapes and drive. You *really* want to
either a) increase your holding space to accomodate your biggest DLE
or b) split your over-large DLEs into multiple holding-disk-sized
DLEs.
--
Joshua Baker-LePain
QB3 Shared Cluster Sysadmin
UCSF
