Is it wise to combine internal HDs with different RPM/cache sizes?

[fernande-mac]

I would like to replace the two internal 160 GB HDs in my PowerMac dual 1,8GHz PPC.

Originally, I was looking for two identical HDs for a software RAID-0 and an external HD for backup (time machine).

However, considering the massive storage sizes of disks nowadays, I am thinking of a 300 GB WD Velociraptor as the main boot disk, and a 1TB WDC Black as the backup disk.

These two HDs have the same transfer rate (3 Gb/s), but differ in RPM (10,000 RPM vs. 7,2000 RPM) and cache (16 MB vs. 32/64 MB). Is it OK to have such internal setup? Or will the "slower" HD affect overall performance?

If it is OK, can I partition the 1TB internal HD to use one portion for Time Machine and the other one for pure direct storage? For instance, I would like to use Time Machine for everything except my music and photo libraries and the rest of the disk to hold a duplicate copy of my libraries.

Thanks!

[rowsdower]

Originally Posted by fernande-mac

These two HDs have the same transfer rate (3 Gb/s), but differ in RPM (10,000 RPM vs. 7,2000 RPM) and cache (16 MB vs. 32/64 MB). Is it OK to have such internal setup? Or will the "slower" HD affect overall performance?

They will operate at their respective speeds regardless of what other drives are in the system. Stuff that is on the faster one will load faster and stuff that is on the slower one will load slower. In this situation, most people try to analyze what they typically do with the computer and put the most frequently used stuff on the faster drive. For most people that includes the operating system and applications, as opposed to documents. However, if you do a lot of work with large files (e.g. video editing), you may want to put data on the faster drive.

Originally Posted by fernande-mac

If it is OK, can I partition the 1TB internal HD to use one portion for Time Machine and the other one for pure direct storage? For instance, I would like to use Time Machine for everything except my music and photo libraries and the rest of the disk to hold a duplicate copy of my libraries.

You can partition it however you want. Keep in mind that the most common types of hard drive failure are catastrophic, meaning that having two copies of something on the same drive will not help you. Don't try to back up the same data on the same drive. If you just want Time Machine so that you can revert to older versions of your files, that will work fine.

[fernande-mac]

Originally Posted by rowsdower

They will operate at their respective speeds regardless of what other drives are in the system. Stuff that is on the faster one will load faster and stuff that is on the slower one will load slower. In this situation, most people try to analyze what they typically do with the computer and put the most frequently used stuff on the faster drive. For most people that includes the operating system and applications, as opposed to documents. However, if you do a lot of work with large files (e.g. video editing), you may want to put data on the faster drive.

Thanks for the clarification. I was planning to use the faster drive for everything and the slower drive for backups.

Originally Posted by rowsdower

You can partition it however you want. Keep in mind that the most common types of hard drive failure are catastrophic, meaning that having two copies of something on the same drive will not help you. Don't try to back up the same data on the same drive. If you just want Time Machine so that you can revert to older versions of your files, that will work fine.

Perhaps the term "duplicate" was confusing in that context.

My idea is to have all the files in the faster drive. Including my music and photo libraries.

The backup drive would be used for two purposes:

• time machine for everything except the music and photo libraries
• a direct access partition with a copy (from the main drive) of the music and photo libraries

I just don't care about the history in time of my music or photo libraries. Only of the other files.

So, the whole backup drive will basically be a duplicate of the main drive. However, there are no duplicates of data between time machine and the data portion.

I hope this is better explained.

Thanks!

[fernande-mac]

So, it is OK to have a dedicated partition for Time Machine and another partition on the same HD for other operations?

[Tesselator]

Originally Posted by fernande-mac

So, it is OK to have a dedicated partition for Time Machine and another partition on the same HD for other operations?

Yes, as long as the TM partition is not sharing a drive with other partitions that are being backed up to the TM partition.

BTW, you can BU a partition that's on the same drive as the TM partition, it's just not very useful and it's about half speed from normal.





.

[fernande-mac]

Originally Posted by Tesselator

Yes, as long as the TM partition is not sharing a drive with other partitions that are being backed up to the TM partition.

BTW, you can BU a partition that's on the same drive as the TM partition, it's just not very useful and it's about half speed from normal.

Cool. Thanks. This makes the thought of a large capacity HD more manageable.

[OrangeSVTguy]

Just remember that the G5s are only rated to 1.5gbps SATAI speeds. You won't get the faster SATAII performance so it's only limited to the G5s speed. I have 2x 500gb setup in a RAID0 and the performance seems decent.

Would love to do Rapter drive for Apps/OSX and another drive for my home folder and external FW800 drive for backup.

[nanofrog]

Originally Posted by Tesselator

BTW, you can BU a partition that's on the same drive as the TM partition, it's just not very useful and it's about half speed from normal.
.

One little niggle though. If the drive goes, the data's gone. You can't restore the data from a dead drive, as both the active and backup partitons are on the same unit.


Easier to say this little part, as someone will almost certainly try it, and get burnt.