RECOVERY

[Nobody's Hero]

Hi all,
We decided to test a recovery of an oracle DB. Imagine that! We always use an import/export to recover oracle, this time we wanted to use rman to test times. Well we are running EDM (EMC) oracle backup utility called rman. 112 Gbytes of data took 19 hours. About 6G per hour. Does this sound excessively slow comming from tape? Does anyone get faster restore times using a similar product? We are getting ready to ditch EDM and go with Data Protector 5(OBII). Any replies appreciated. Just wondering if we are dog slow comming from tape.

RPM

[Ian Dennison_1]

What kind of tapes are you restoring from? Even the new LTO-Ultriums only get 25-30MB per second. Are you using compression on tape drives? What intermediate steps are between the Tape and the destination Disk?

Are you striping disks down alternate path?

More input please.

Share and Enjoy! Ian

[John Palmer]

It does sound slow, under 2Mb/second. What sort of tape drive are you using and how long does it take to back the database up?

Regards,
John

[John Poff]

Hi,

The 'rman' utility is an Oracle program. EDM is integrated with it, just like OmniBack/Data Protector does.

Those rates sound awful slow. As Ian asked, give us more details please. We had EDM for a while and we gave up on it and went back to OmniBack.

JP

[Nobody's Hero]

Sorry, DLT7000 on a dedicated FDDI network, 100MB. ATL library SCSI attached, 6 tape drives.

[Robert-Jan Goossens]

Hi Robert-Jan,

Max speed for DLT-7000.
8.3 MB/s
Rman backup/restore

Robert-Jan.

[Nobody's Hero]

using hardware compression only. Disks are striped and mirrored via EMC symmetric, fibre attached to SCSI drives.

[Nobody's Hero]

Takes about 8-10 hours to back it up.

[David_246]

Hi,

Looking at the networkspeed you can say the maximum amount of data you can reach per hour is :

100 Mbit/s = 100 /8 = 12.5 Mbyte/s
But you never reach a 100% bandwith, so 80% * 12.5 Mbyte = 10 Mbyte/s

10 Mbyte * 60 sec * 60 min =
10 Mbyte * 3600 = 36000 Mbyte / hour
3.5 Gb/hour

This is only when looking at a maximum bandwith of a 100 Mbit link. Of course you have to be aware where the (possible) compression is being done, is there softwarecompression done on the client side or on the server side ?? Is there enough cpu capacity on both the backup server as the client ??

When looking at a tapedevice you have to know what type of device you are using; DLT/ Mamoth / DDS ???
Try to find the backup speed. Now you can do the counting.

What in generic you can say is that you have to double your backup-time to get your recover time.


Regs David

[Mark Greene_1]

When you run the restore, do you here the tape starting and stopping and starting a lot? If so, you are I/O bound on the disk side and are not reading the data from the tape fast enough to keep it streaming. The latency imposed by stopping the tape, rewinding it, and restarting for the next read are what is killing your throughput.

mark

[Robert-Jan Goossens]

Robert,

http://otn.oracle.com/deploy/availability/pdf/rman_performance_wp.pdf

Robert-Jan.

[Ravi_8]

Hi, robert

Our sys admin who manages the backup and restore and using LTO.
he says the max speed he gets is 20-25 MB per sec

[Ian Dennison_1]

Robert,

With reference to the previous posting,...

Had an EMC at my previous job with DLTs, and it did take approx 50-100% longer to do a restore than it did for the backup.

Are you using EDM as a SAN based-solution? I assume not, given the mention of 100MB network connection. Do you have the budget / time to look at server-free backups?

http://www.emc.com/pdf/techlib/symm_cflg_wp.pdf

Here's an interesting white paper on EDM, with scenarios included. Note Page 23 where it talks about optimum stripe size; might be worth a look.

Share and Enjoy! Ian