Hello, I am running Netbackup 7.6.0.1 and I configured MSDP diskpools, all the backups go to disk. Later it is duplicated to tape. But there is my problem. Duplication is very slow and it never ends. Sometimes I have more then 100 jobs in that queue which never seem to go so I just cancel them. Is it not possible to have more then one duplication jobs to the same tapedrive? My library has only one tapedrive. Also I see that the tape gets mounted over 100 times and they are in use for just a month. Is there a way to speed up the duplication process? I always thought the images in a MSDP-pool are optimized and they should go to tape fast. Any thoughts? Regards, Rob

You can seed the backup using this method: https://support.symantec.com/en_US/article.TECH144437.html

MSDP images have to re-hydrate before being put to tape, therefore the duplication will be slow as the "restore" part (the re-hydration) will be slower. Why only 1 tape if you have the need to duplicate lots of backups?

Lots of random reads when re-hydrating from MSDP. Have you checked your disk volume for how 'active' it is? use Windows Resource Monitor, in the 'Disk' tab, in the 'Storage' panel at the bottom, you can see how busy a disk volume is. If it's 99% all the time, then you know where your first (only?) bottleneck is.

It does not make sense to have only 1 tape drive if you intent to duplicate most, if not all, data to tape. Add more tape drives.

Even Symantec NetBackup Appliances (which are carefully specified, built, and tuned) are only 'unofficially' capable of driving two tape drives, and this is also 'unofficially' only when they are quiet - i.e. not having to perform backups, and are thus free to duplicate (re-hydrate) to tape. To build your own server capable of reaching these levels, or exceeding them, requires very careful system design, and a pocket full of money to specify/purchase/build a powerful server. Here's a simple calculation, which assumes that your server is even capable of this... so if you have 10 TB to duplicate to tape, and you have have a server capable of re-hydrating (sustained random read IOPs/throughput) and thus capable of reading MSDP disk at 120 MB/s - to match the typical minimum sustained write throughput of 120 MB/s to one LTO6 tape drive - then if you had 10TB to duplicate to tape, it would take 24 hours: 10.0 TB 10,240.0 GB 10,485,760.0 MB 120.0 MB/s 87,381.3 seconds 1,456.4 minutes 24.3 hours How much data do you have which must be duplicated? And you need to be mindful that if a server (and it's storage (which MSDP resides upon)) is only capable of, for example sustained random read of 60 MB/s, then a duplication will take on average 48 hours - but then this also assumes that the tape drive itself is capable of 'speed streaming matching' down to 60 MB/s. If the tape drive is not capable of physically running slower in 'streaming mode' - then shoe shining will take place, which will greatly increase the elapsed duration of the duplication. FYI - FH (full height) and HH (half height) LTO tape drives have quite different capabilities and charactertistics. Also, IBM LTO drives and HP LTO drives and Quantum LTO drives (etc...) have different 'speed matching' capabilities - e.g. some can speed match to 60 or 80 or 100 or 120 or 140 or 160 MB/s - whereas some can only speed match to 75 or 150 MB/s. So, if one has a tape drive which has a minimum speed match capability of 75 MB/s and a server only capable of sustaining 60 MB/s, then shoe shining will occur for the entire duration of the duplication, and massivley increase the duration of the duplication job - and wear out both the tape drive head itself and the tape media at a much much higher rate.

Hello, Sorry for not getting back sooner. I had a support call about this issue. We found out that the disks are fast enough. One issue we found was that we have some very slow backups. Some systems take more then 20 hours. Support told me that those slow backups to disk will also be slow duplicated to tape. Support recommended me to investigate what the buffer-size should be and configure it accordingly https://support.symantec.com/en_US/article.TECH18422.html So now I need to find out what the buffer-size should be for LTO3, LTO4 and LTO5 tapedrives. Also indeed they said that just 1 tape-drive is a little bit less. Would it not be possible to have multiple stream from the disk to tape while duplicating? Best regards, Rob

duplication to tape

15 Replies

sdo
Moderator
10 years ago
Yes - duplicating to MSDP within the appliance will capture a 'de-dupe' copy.

If you enable client side de-dupe on the client then only new different blocks will be sent via LAN/WAN to MSDP server.

If you do not enable client-side de-dupe then all data of a full backup will be sent to the MSDP server (via LAN/WAN) which will do the de-dupe discard of already known blocks.
Rob_Dullaart
Level 5
10 years ago
What I did was, I made a full accelerated backup at the remote location, with client-side dedup enabled.
Then I brought the mobile media server to our datacenter.
Next step was duplicate the backup-images with this command

bpduplicate -backupid <BACKUID> -dstunit <STORAGE_UNIT_DATACENTER>

The policy is configured to write to this STU in the datacenter. Now I started the policy to see if it works.
But in the log I see this "There is no complete backup image match with track journal, a regular full backup will be performed."

But it looks like not much data is going over the line. Because only the counter of "Current files written" is going up. None of the other counters is going up, not "Current Kilobytes Written, not "KB/Sec"

So it looks it somehow works, what do you think? I am a bit worried about that message that it's going to do a full.
sdo
Moderator
10 years ago
Sounds like your plan is working Rob. Fingers crossed it goes as planned.

If client side de-dupe is enabled (i.e. not disabled in policy, and the master server 'Client Attributes' for the client name is either 'Prefer to use client side deduplication' (and the required ports are open) or is 'Always use client-side deduplication' (which will fail if the required ports are not open) - then not much of anything should actually go over the wire.

Whenever a client is added to a new policy name (and this includes the action of deleting the client name and re-adding the same name back to the same policy) - then NetBackup considers the situation as a full backup is required. No avoiding it.
Andrew_Madsen
Level 6
10 years ago
You can seed the backup using this method:

https://support.symantec.com/en_US/article.TECH144437.html
Rob_Dullaart
Level 5
10 years ago
This looks like what I tried to do, it looks pretty complicated and I need to do some thorough reading.
For this time it is to late, I allready went to the remote site and made a backup and I brought this backup to our datacenter. The first backup I did took 38 hours for one server. The next took about an hour. This was one of the two servers at the remote site, the other server has about 5 times more data. Estimating that would take 200 hours to finish. :( the only benefit I see now is the depuplication. The backup of the first client only sent about half the amount of data.

Or would it be posible to speed it up without going to the remote site again?

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duplication to tape

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