What is the perfect sized file to back up?? 1

[mrslimey]

I have question which relates to the best sized file that Back Exec 9.1 can write to tape. Tape type LTO 200GB.

Reason for asking is that I have the option within Enterprise Vault to make collections of lots of small files and save them to a larger cab file.

Look forward to your answers.

Mr S

 

[Zelandakh]

The overhead to backup small files is quite large (so to speak) so in theory the larger the file, the less time wasting there is, so the faster transfer rate you get. But to compress the data into zip files also requires overhead. If you are doing that on the fly you need a really fast server with loads of RAM and lots of really fast disks.

Why not try backing up the data then get EV to save it all to CAB and re-run the backup and compare the times.

LTO 200GB. Not sure if that is LTO-2 or LTO-3 but I'm seeing about 5,000MB/min off my LTO-2 on large files.

 

[Santei]

Hi there!
sorry man, butr i do not understand what are u really looking for.
have u already bought back up soft?

 

[mrslimey]

Hi Santei,

Refer to Zelandakh as he puts it nicely.

The question is as follows....

If i have say one hundred 1MB files and one 100MB file which will back up faster when using BExec.

Theory is that it will be faster to back up the one 100MB file as it only has to do a single read but then this may depend on the buffer size available to BExec etc.

However I would like to know if anyone has a definitive answer?

 

[Santei]

ha, I c,thx for explanation.
no doubt u'll win time if u back up 100MB file.
there is another way to behave
if u aren't sure in BExec.
i can advice to download demo version of this http://www.acronis.com/homecomputing/products/trueimage/"]backup[/URL].
it works very quickly. i'm using.

 

[Zelandakh]

There is no definitive answer. To take yours further:

1MB x 100. Backup 100 files.
100MB x 1. Compress 100 files into 1 file. Backup 1 file.

This will depend on the architecture of the hardware. Try it on your system and see. Your answer will be different from mine as I run different hardware.

 

[justin2000]

I thing to note with EV - the cab file size you create is the maximum size - with the latest EV6 Sp2, the mx cab file size is 99mb.

From experience, you will find that you will rarely hit the maximum cab file size.

What will kill your backup speed is the Index locations - backing up hundreds of small files - each index location will have a max of 250 files. Would suggest for this to only backup the index locations, maybe once every couple of weeks.

As for size - backing up large files is always going to be faster than alot of small files.