* William Taylor <[email protected]> [20100222 13:12]:
> I seem to be having some issues with amanda getting data off my drives in a
> reasonable time.
> using dd reading off my drives and writing to tape I get around 120mbs to the
> LTO4 drive.
> When using amanda however this number fluctuates quite a bit. At times I have
> seen it write to tape
> at around 110mbs but it's usually around 40 or so.
OK, I'll bite.
Hardware: SuperMicro X8DTN, 2xQuadCore Xeon 2.27GHz, 12Gb Ram
Overland ArcVault48, 2 HP LTO4 drives, LSI Dual port
U320 scsi HBA.
OS is Debian/Lenny with kernel 2.6.31 64bit.
I'm running amanda-2.6.1p2 and I routinely get +100MBps from a
holddisk to LTO4. An HP LTO4 will stream when speed to tape is
40-120MBps. To get around and above 100MBps you really need to tune
your holddisk/hardware and kernel IO. I use a 4-spindles striped
logical volume, Seagate 1TB Sata disks, with XFS on top of it, tuned
again to get max output. The disks are on a inboard backplane inside
the server. Note that I use hardware compression on the LTO4 drives
but these drives are smart so I don't think it matters very much.
I use tape_splitsize=10GB but I don't think this is relevant in terms
of performance. blocksize=2048MB but again my tests never showed
significant differences in the range [512MB-2048MB]
My advice: you won't get anywhere until you tune your holddisk.
This is the major bottleneck! The holddisk is your friend!
LTO4 drives are *fast* and you need to carefully tune your hardware IO
stack to get them close to max performance. That is, once you have
validated your tape drive and scsi path to them, HBA, cabling, etc...
hth,
jf
>
> I have tried several different configuration options and none seem to really
> improve the situation.
>
> I am using amanda to do local backups.
> I have a bunch of large (+2TB) netapp dumps on a 24 disk 16T raid5 array
> connected to a 3Ware.
> I have also configured a 14 disk netapp shelf with 15k scsi drives striped
> with software raid connected via a 2GB fcal to use as
> a scratch disk to break up dumps or to use as a holding disk.
>
>
> Can anyone recommend amanda config options that would work with my setup?
> So far it seems that best results are achieved without using the holding disk.
> I have tried setting the tape_splitsize to 4Gb and fallback_splitsize to 8Gb
> with no
> real change in performance. I have 12GB of memory.
>
>
> Heres the relevant bits I have so far:
>
> netusage 100 mbps
> device_output_buffer_size 1 Gb
> tapedev "tape:/dev/nst0"
> device_property "BLOCK_SIZE" "1024k"
>
> holdingdisk hd1 {
> comment "main holding disk"
> directory "/scratch/"
> use -100 Mb
> chunksize 80Gb
> }
>
> define tapetype LTO4 {
> comment "Dell LTO4 800Gb - Compression Off"
> length 802816 mbytes
> filemark 0 kbytes
> speed 120 mbps
> blocksize 1024 kbytes
> }
>
> define dumptype user-tar-span {
> #holdingdisk no
> root-tar
> tape_splitsize 80 Gb
> split_diskbuffer "/scratch/"
> #fallback_splitsize 8 Gb
> priority medium
> }
>
>
> If I need to provide anymore info let me know.
>
> Thanks,
> William
