Forum Discussion

schrammd's avatar
Level 5
12 years ago

What is the fastest you've seen Flash Backup run (*nix)

We see stellar bandwidth off any combination of disks for LUNs/volumes of 500GB or less. The jobs will rip blocks as fast as the host and subsystem allows. But, take 2 metaluns striped accross 24 15k disks and the overall backup rate is the same as if I gave it an 8+1 RAID5 group on 10k disks. This makes no sense to me so I am asking the community how fast have you ever seen raw volume backups run?




3 Replies

  • I don't think backup is the issue here. If two different storage layout provide the same backup speed you got a bottleneck somewhere in the OS/Storage layer.

    Have you tried dd from the raw device ?

  • Well, the backup is the issue. I've tested the raw devices with dd and with flashbackup to compare results. dd can read the volumes 2x what flashbackup can. The point of FBU is supposed to be elimination the FS overhead but this is not the case accross the board. As I said, in a bunch of testing I've done recently, in fact on 2 completely different media servers, domains, storage frames, LUNs, whole 9 yards, the results are the same. Small LUNs/volumes rip data off at the same speeds whether using dd or FBU and this is considerably faster than a Standard UNIX file system backup. But beging to use larger LUNs and the performance "advantage" seen  basically disappears to the point where there is no point in using FBU yet the underlying storage is more than capable of saturating any backup target FBU is writing too.


  • Please tell us more detail about your configuration like residence and role of host, network and FC bandwidth, backup destination storage or so. Also provide transfer rate you got in both backup.

    Have you already tuned shared memory buffers? Have you already measure Media Server performance using GEN_DATA directive on it or using SKIP_DISK_WRITES touch file?