On Wed, Sep 21, 2011 at 12:14 AM, Yaron Zabary <yaron AT aristo.tau.ac DOT il>
wrote:
> As a side note, I don't really see how you will be able to feed 4 LTO5
> drives. You didn't say which hardware and OS you will be using, but keep in
> mind that LTO5 is 140MBps native (the 2009 draft suggested 180MBps) which
> means you will be trying to push ~500MBps from your array and server. This
> will require you to optimize your setup or even replace or add hardware.
We currently have 4x LTO3 fed by a 1 Gb metro link, so they are either
shoe-shining like crazy or we multiplex so many save sets onto a
single tape that restores become a very drawn out process. If the
array can keep one drive fed with sequentially staged savesets then
we've made a great improvement :)
I was hoping to keep things simple and use just a single device, but I
can only associate a single staging policy with a single adv_file
device, and hence only a single destination staging pool? Is there a
recommendation for how many adv_file of what size I'd need (aside from
1 per staging destination pool) :)
About setup:
We are RHEL6.1, using XFS.
mkfs.xfs options were: -l version=2 -d su=128k,sw=11 to match the 11
spans of RAID10 and 128kb RAID stripe (appears to match the 128KB
block size of adv_file devices as according to the Tape Configuration
Guide, that can't hurt right?)
mount options are:
rw,noatime,nodiratime,logbufs=8,logbsize=256K,nobarrier,osyncisdsync
I'd have to reboot with mem=256m again to verify, but the last
sequential read was 480mbytes and sequential o_direct writes a little
over 550mbytes. Hopefully we'll scale this to another 12 or 24
spindles in the not too distant future...
Thank you,
Eugene
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