File device class vs disk device class

[yquirion]

Hi all,

We have around 10TB of disk space available for our new TSM 6.2.x server. I would like to know the best practice on how to assign that disk space.

A feature that is interesting is the data deduplication. I know that, for this, we need to have a device class of type file. I would like to know the best setting for such device class. In the past, we were only using DISK device class for our disk pools.

Is there any performance using FILE device class versus DISK? When we are creating a device class of type FILE, the "Device Access Strategy" is "Sequential". Is that faster than DISK device class which is "Random"?

In short words, you have 10TB of space disk for TSM, how would you like to use it?

Thanks you very much for your help.

Best Regards,
Yanick

 

[BBB]

There is a comparison of file and disk device classes in the TSM information centre which is very good, just read that - and yes there are significant advantages and disadvantages to both types.

When planning make sure you account for the amount of time and extra db space that deduplication will require.

 

[Jeff_Jeske]

All of our disk_pools are random. Other than that all off our disk based storage including content manager are file device class. We have had no performance issues with SATA disk file device class storage pools.

 

[abdoyones]

disk

i think disk device class is better than file especially when backing up or restoring multiple clients at the same time.
if i were you i would use disk device class .
Best regards

 

[mateinone]

i think disk device class is better than file especially when backing up or restoring multiple clients at the same time.
if i were you i would use disk device class .
Best regards

That statement is way to broad. You can make small "files" and have as many mount points as you require, so that is not as big an issue as people make out and personally I think that there is a time and a place of both. In saying that, there is absolutely no question in my mind that the "whitecoats" are heading towards a strategic direction of FILE

 

[mikeatkc]

i think disk device class is better than file especially when backing up or restoring multiple clients at the same time.
if i were you i would use disk device class .
Best regards

TSM Administrator's Guide, p.71-76 contains comparisons, etc. Enjoy.

 

[GregE]

In saying that, there is absolutely no question in my mind that the "whitecoats" are heading towards a strategic direction of FILE

Who do you mean? IBM?

I'm currently looking at options for a data center transition, the result being TSM in two data centers, one as a DR site (and replicated) site. FILE device class is very attractive for what we're going to be looking to do.
http://adsm.org/forum/showthread.php?t=20597

 

[GregE]

That's very interesting, thank you. I was thinking the opposite, which was that they would push away from FILE to enhance their VTL sales. But I guess there's plenty of room for VTL and FILE is way too important.

 

[GregE]

Performance When All Else Equal

I've read the comparison chart, but if ALL else is equal, is there a performance difference between FILE and DISK device class during backups? Types of data would be Oracle, MSSQL, and filesystem (Unix/Windows).

 

[Jeff_Jeske]

Sure.... file device classes seem to handle sequential reads and writes better.

99% of our restore requests are for a single server or single file. Full server DRs are rare and multiple servers DRs are even more unlikely. For my company file device class is the most efficient method to handle the most common restore.

 

[lepeshk]

Were you set devclass in library

Yes, he means IBM. I've looked at some slide decks (going as far back as 2005) in which the IBM presenter mentions that FILE is the direction in which TSM is heading.

WERE you set devclass in library.

 

[lepeshk]

Difference between clientopt and clopset

Sure.... file device classes seem to handle sequential reads and writes better.

99% of our restore requests are for a single server or single file. Full server DRs are rare and multiple servers DRs are even more unlikely. For my company file device class is the most efficient method to handle the most common restore.

anybody plse help me on this difference betwen clientopt and clopset.

 

[lepeshk]

policy management class step by step in command.

[QUOTE
anyone explain me policy management class step by step in commandline.

 

[nico741019]

Throughput idea

Hi, could someone give me the sustainable throughput for a file device class on SATA and on SAS/FC? We would like to replace 10 old IBM 3590 drives by a file device class, but we are not sure about performances.
Thanks.

 

[ad283m]

It depends, because for somethings like a database dump you cannot use a disk devclass

 

[Jeff_Jeske]

It does depend on a bunch of variables.... I suspect you would be using 2TB drives in a raid 6 configuration. Then you would have to ensure that you don't over work a particular raid group or service processor. We would need to know the fabric design and speed as well as the overall utilization of the frame.

So... I can't really answer your question. I can tell you that our sata is dedicated to the tape fabric. A good number of our databases feed directly to Sata as do our TSM Disk Pool migrations. Our frames eat that up and ask for more without a blip on the radar screen and our equipment is fairly aged. I don't know how much data you are talking about streaming but SATA is very good at laying down large contiguous files.