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Frecover taking too long

 
sysad_boy
Frequent Advisor

Frecover taking too long

Hi,

I am restoring 2 files from a backup DLT tape and running frecover for more than 24 hours now.

The backup is made out of 5 tapes and took 14 hours to produce.

Does restoration really takes this much time? as of this writing my frecover command is still running and is reading volume 3 out of the 5 backup tapes.

BY the way here is the command I executed:

/usr/sbin/frecover -xvF -f /dev/rmt/3mn -g restore.txt

where restore.txt contains the files i am restoring:

#cat restore.txt
i /home/ccb_oper/.ssh/id_rsa
i /home/ccb_oper/.ssh/id_rsa.pub

What can I do to speed up recovery?
11 REPLIES
F Verschuren
Esteemed Contributor

Re: Frecover taking too long

sorry I do not think there is a way to speet up the restore ad this point,
For the future, may be it is better to split up the backup so you can use 1 tape per backup and yo do not have to read in all tapes...

For now waiting is the best way to go.
sysad_boy
Frequent Advisor

Re: Frecover taking too long

Is there a way I can find out of frecover hasnt hang-up yet?

everytime i execute mt -t /dev/rmt/3mn status, i always receive a "on tape open: Device busy"

and another question is why is it that volume 1 and volume 2 was read faster (2 hours for the 1st 2 tapes combined) compared to this volume 3?

frecover command is reading this 3rd volume for 20 hours or more.

The first time I tried restoration it also took this long for the 3rd volume and i thought frecover hang-up and restarted the process. Now I am trying to be a little more patient this time.

Re: Frecover taking too long

>Is there a way I can find out of frecover hasn't hang-up yet?

Do you hear/see the tape moving?

One trick you might be able to use is to mount the last tape first. That tape should know where every file should be.
Bill Hassell
Honored Contributor

Re: Frecover taking too long

Because this is a multi-tape backup, only the last tape knows where all the files are stored by tape number. As Dennis said, you put the last tape in and then run the command. frecover will read the index and ask you to put the correct tape in -- if the files are on the last tape, it will start reading.

However, unless you defeated the search mark capability in fbackup, frecover will position directly to the beginning of the files in a couple of minutes. On a 5 tape backup, I would expect recovering those two very small files would take less than 5 minutes.

To defeat fbackup search marks, you probably made a backup over the network and that gives you two hits on performance. The first is that the network is probably too slow for the tape. Unless 100% of the connections (source, in-between and destination) are 1000Mbit speeds, the DLT had to pause and backup every time data was delayed.

The second hit is that high speed search marks are not written across the primitive tape-to-tape connection provide with fbackup/frecover. This defeats the most powerful feature of the fbackup/frecover tool -- high speed searches.

However, 24 hours definitely indicates a problem, probably a bad tape. Unfortunately many brands of tape drives do not provide useful status. I would terminate frecover, use a cleaning tape and then put the last tape in the drive and restart your restore. If the files are on a different tape, frecover will tell you.


Bill Hassell, sysadmin
sysad_boy
Frequent Advisor

Re: Frecover taking too long

Now i tried re-running the restoration starting with Volume 5, however it prompted me that it expects volume 1.

Problem is after Volume 1 I am sure it will ask for Volume 2 and afterwards Volume 3 once again. I hate this volume 3, i think there is something wrong with the tape.

Now I have an alternative, is there anyway on how to recover the id-rsa and id_rsa.oub files aside from restoring from backup?

Does HP-UX automatically creates its own backup of this file of some sort hidden in some sub directories that we normally don't visit?
Patrick Wallek
Honored Contributor

Re: Frecover taking too long

>>Now I have an alternative, is there anyway
>>on how to recover the id-rsa and id_rsa.oub
>>files aside from restoring from backup?

No, not that I know of.

>>Does HP-UX automatically creates its own
>>backup of this file of some sort hidden in
>>some sub directories that we normally don't
>>visit?

Again, no, not that I know of.
TTr
Honored Contributor

Re: Frecover taking too long

>Now I have an alternative, is there anyway on how to recover the id-rsa and id_rsa.oub files aside from restoring from backup?

It depends what these files were used for.You can use the ssh-keygen command. However if these two files contain keys that were generated using a specific passphrase, you have to know the passphrase.
If the ccb_oper person is no longer with your company then you are out of luck.
sysad_boy
Frequent Advisor

Re: Frecover taking too long

it does not contains a specific passphrase, only it is being used for a passwordless login to pull files from this server.

My problem is there are many servers using this same user name, to connect and pull data from this server I am having problems with.
TTr
Honored Contributor

Re: Frecover taking too long

Then you would need the "authorized_keys" file not the two you are trying to restore. Take a look at http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch17_:_Secure_Remote_Logins_and_File_Copying#Using_SSH_and_SCP_without_a_password

You still need to fix the way you do the backups and restores. Maybe adjusting the file markers during the backups would speed up your restore. You should also test and document the restore process specifically to your multi-tape set. Having a set of backup tapes is not enough.
Bill Hassell
Honored Contributor

Re: Frecover taking too long

> Now i tried re-running the restoration starting with Volume 5, however it prompted me that it expects volume 1.
>
> Problem is after Volume 1 I am sure it will ask for Volume 2 and afterwards Volume 3 once again. I hate this volume 3, i think there is something wrong with the tape.

This definitely sounds like you did not run a normal fbackup but instead ran it through a pipe or used the remote tape feature. Either of those methods inhibits creating setmarks and thus you have to read through each tape serially. If the backup was stored on a tape drive connected to this server, you would only need a few minutes to restore the files.


Bill Hassell, sysadmin
F Verschuren
Esteemed Contributor

Re: Frecover taking too long

Just a tough,
Do you also run Ignite backups for this server where /home is included, if so you can tar it form the ignite tape/file...

If /home/ccb_oper is a link, it is better to give the real position (like /volumes/home/ccb_oper/.ssh)

ps if it is a link the ignite option only works id the real please is included...