neil lehrer wrote:
hi,
i am testing ndmp backup solutions on my f760[part of a cluster] running 5.36r2, against a spectralogic treefrog. questions:
- once backup started sysstat 1 showed cpu util at about 40% during mapping and
initially 100% during dump for about 2-3 minutes and then much lower numbers since then. is the 100% util normal? nothing else is running, system is not prod yet.
The first stage in an NDMP backup is a snapshot creation of the directory/tree/path that you are backing up. This is very CPU intensive and it is not uncommon for a single snapshot creation to consume all the available CPU resources. NetApp recommends that you have a maximum of four NDMP sessions running on a filer at one time (on a F760, only 2 on a 740 or 720). Even with all four NDMP sessions running at the same time, our users rarely notice, even though the CPU is pegged. This may be different in your environment as we are using purely NFS, no CIFS of HTTP, on our filers; these other protocols may be more CPU intensive and may respond differently to something else hogging the CPU.
- can ait2 tapes be "bad" fresh out of the wrapper? the software would not
handle 1 of the tapes, backup vendor said tape was probably bad. what is the ndmp response to a "bad" tape?
I do not have much experience with AIT-2 tapes, but I can imagine that it is possible for a tape to be bad straight out of the box. As far as how NDMP handles a bad tape, in my experience it reports an error code which is interpreted by the backup software.
- is the chip in the ait tapes used by ndmp backup?
Again, limited experience with AIT tapes, but I can't imagine that NDMP is elegant enough to make use the MIC. Of course, with the latest implementation of NDMP in ONTAP 6.x, NetApp has (re)introduced support for Direct Access Recovery (DAR), which serves a similar purpose as the MIC in the AIT tapes. DAR writes periodic updates about which file it is writing, and can from this information, move the tape directly to the approximate location of the file you are restoring. Unfortunately, DAR does have some limitations, chiefly that it is constained to restoring files (not directories), and it is limited to roughly 1000 files at a time. But for restoring single files, it can't be beaten.
Geoff Hardin Dallas Semiconductor MIS UNIX geoff.hardin@dalsemi.com