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September 29th, 2019 08:00
networker (latest) - is "parallel cloning" of a single saveset (vProxy VM image or BBB) possible ???
Hi there,
I wonder whether this can be done somehow...
The scenario: one single Vmware VM, one large filesystem, currently backed up to Data Domain (using vProxy/image backup, DD BOOST), and a new need to clone this backup (or whatever kind of backup of this VM) from DD to tape, on a daily basis. (Traditional agent-based, file-based backup is basically ruled out: too many files, storage too slow for that, only one filesystem - no organization of data into multiple FS's, file-based backup - even incremental - would take ages to build the file list & manage file index.)
The problem with the new need (to clone very frequently to tape): this is a large saveset (some 15TB+), and to our knowledge, cloning a vProxy VM image from DD to tape is a single stream operation. (Single stream DD performance is quite bad in our case - the performance guide says 80+ MB/s for Windows and 200+ MB/s for Linux, for the maximum configuration of DD6300. Of course, this actual config is much smaller than that maximum.) The new requirement is to clone this 15+ TB VM image to tape on a daily basis. (The vProxy/NVP backup to DD is CBT-based, virtual synthetic full. So we should clone the virtual full, i.e. the whole 15+ TB every day.)
We were recommended to switch to block-based backup, where we have the option to do pss parallel save streams. (Multistream read/recovery performance of DD is much-much higher, than single stream.) So backup will be similarly fast as (or even faster than) with vProxy. And in that case we will be able to do parallel cloning.
Well, I did not find any details in the docs (Documentation Portfolio) whether parallel cloning of PSS-based BBB block-based backups (parallel cloning of a single saveset) is possible, whether enabling RPS for that is needed, or how to set that up/what params to tune. We did some tests, but those cloning operations did not seem to be parallel, and were damn slow (obviously single stream) from DD to tape.
Any hints, experiences?
Thx.
crazyrov
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September 30th, 2019 05:00
I might have to test this behavior and get back to you.
bingo.1
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September 30th, 2019 12:00
I do not see any way how to run a parallel cloning process of a single save set. And VNP creates a single save set.
The only possibility to achieve very fast cloning is to get away from tape to another disk based clone media, like ECS for example. If both devices/volumes are stored on the same DD, cloning will just take a few seconds/minutes. But this of course is another approach and it needs more investment/money, of course.
Geza Balazs
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October 7th, 2019 07:00
Hi,
the focus is: produce a clone either offline/offsite (e.g. tape, vault), or on a file share/Networker AFTD advanced file type device (i.e. outside of data domain).
Whatever we tried, cloning a single save set from DD (= single-stream read) was damn slow.
I can not see any way out, to satisfy this new requirement, with the current setup (Networker + DD).
bingo.1
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October 8th, 2019 04:00
15 TB/day = 625 GB/h = 174MB/s
So with an LTO8 you should be able to achieve the challenge for the destination device.
However, the DD will be used for backups and other processes during the day so the achievable read data rate is obviously less. This is valid for a single save set.
Using PSS you can get a much faster backup speed but you have to deal with independent save sets (default = 4). To achieve faster clone speeds, you have to run multiple clone processes (nsrclone commands), one for each save set and ... ideally ... sending each save stream to another tape drive. This should work but I would expect a decrease for the read speed (from the DD) now. No idea how huge it could become.