backup very slow

[siva baskaran]

Dears,

we using tape array 5300 in rp4440 server actually we had to take backup only 250gb size but it taking very long time like 9 hrs for to be completed 30 or 40 %, and we are using vxdump command file system is vxfs and drive speed is 80 gb/hrs.
command is

vxdump -0uf /tapepath /filesystem
so please anybody give me solution for taking back up as much as fast

thanks
siva

[JASH_2]

Siva,

How is the array attached to the server? Is it on a san, or just by lan.

I have had this problem before, when the network card on the server has gone to simplex instead of duplex, or negotiated down to 10 instead of 100 mbs.

Regards,

JASH

[Patrice Le Guyader]

Demat,

Use this tool if you want to make some test. After you will know if you tape array have some trouble.

http://h18006.www1.hp.com/products/storageworks/ltt/index.html

Hope this helps
Kenavo
Pat

[siva baskaran]

Dear,

this tape array is attached internally in the rp 3440 server using SCSI cable

thanks
siva

[Bill Hassell]

What tape drive are you using? The 5300 is just an enclosure that supports these tape drives:

DAT 40
DAT 72
Ultrium 215
Ultrium 448
Ultrium 960

Here are the MAXIMUM data rates possible with each drive:

DAT 40 10-20 Gb/hr
DAT 72 10-20 Gb/hr
Ultrium 215 27-54 Gb/hr
Ultrium 448 54-108 Gb/hr
Ultrium 960 100-216 Gb/hr

None of these drives matches your drive speed specification. NOTE: The only guarenteed performance for the drive is the lower number. The higher number will never be reached unless you have specific data patterns in your data files that allow 2:1 compression. Also, you will never reach ths higher speeds if your computer and backup program cannot maintain data flow faster than the tape drive needs.

For a network backup, the LAN will cripple your tape drive. Here are the maximum backup rates for the 3 popular LAN connections:

10 Mbit = 0.5 Mbytes/sec = 1.8 Gb/hr
100 Mbit = 5 Mbytes/sec = 18 Gb/hr
1000 Mbit = 50 Mbytes/sec = 180 Gb/hr

The calculations are Mbit / 10 = Mbytes at 50% saturation (typical for a switched LAN connection). As you can see, 180 Gb/hr is too slow for the Ultrium 960 if your data is highly compressible.

The Ultrium tape drives are so fast that many systems just cannot keep up with the maximum speed so they have a rate adaptive feature (the tape speed is reduced if data is too slow). The DDS and most DLT drives do not have this feature, so when the drive runs out of data (computer is too slow) then the drive stops, backs up, and restarts, a very slow (seconds) task where nothing is recorded. If this occurs every few seconds, the overall backup speed can be less than 1/100 of the normal speed.

Finally, if your backup is local (not over the network), if the system is busy, the disks may not provide backup data fast enough. And vxdump is a single threaded program which means that files are opened and copied to the tape drive one at a time. Open/close operations will slow down the backup if the files are small.

An alternative to vxdump is fbackup. This is the only high speed file backup program supplied with HP-UX and allows up to 6 independent reader programs to keep the data path (through shared memory) full at all times. Ity must run with a config file for maximum performance:

blocksperrecord 4096
records 64
checkpointfreq 4096
readerprocesses 6
maxretries 5
retrylimit 5000000
maxvoluses 200
filesperfsm 2000

Run fbackup with -c conf_file for maximum performance. And unlike vxdump, fbackup seamlessly handles multiple tapes in a backup session, has an instant index on every tape, prevents accidental overwrites of a previous tape and writes a data checksum for every block written to tape. fbackup also has errot recovery for locked files and bad spots on the tape (frecover).

[siva baskaran]

tape drive is 960 ultrium (3 format), and is fullfill my requirments which are full backup that means i should take file system dump, is it full fill ?

thanks
siva

[siva baskaran]

Dear,
when i using fbackup cmd by through SAM, it giving bellow mentioned error so now what will be problem

fbackup(3013): WRITE ERROR while writing data record, at media record 296

fbackup(3102): attempting to make this volume salvagable

fbackup(3103): rewrite this volume from the beginning?


thanks
siva

[JASH_2]

Siva,

Looks like a bad tape.

Regards,

JASH

[Torsten.]

Where is the tape drive connected to your server (slot/port)?

Please provice an

# ioscan -fn

[Torsten.]

Where is the tape drive connected to your server (slot/port)?

Please provide an

# ioscan -fn

[Bill Hassell]

The fbackup messages indicate a write error in the tape drive, probably due to a bad tape. Run the cleaning tape and try again. If a new tape fails, the drive is probably bad. It might also explain the extremely slow speed of the tape drive -- it is retrying and erasing the error locations on tape.

The Ultrium 960 will work OK in this situation. The capacity of the tape is about 400 Gb (literature says 800 Gb but that's with special data patterns). The data rate is 80 Mbytes/second minimum but you'll need at least 160 Mbytes/sec most of the time to handle any possible data compression that can be done by the tape drive. This tape drive can slow down to as little as 27 Mbytes/sec if necessary. From the HP Ultrium 960 data sheet:

"Data Rate Matching (DRM): Allows the tape drive to dynamically and continuously adjust the speed of the drive, from 27MB/s to 80MB/s, matching the speed of the host or network."

At the slowest rate, you'll get about 97 Mbytes/hour as long as your data gets to the drive fast enough. If your disks can supply the data fast enough, you should be able to backup 250 Gbytes per hour.