Drobo

A strange speed problem and file system question

Hello all…

I have a question regarding speed and file systems that someone might be able to answer.

I have a second generation Drobo attached to my iMac via FW800. I know the Drobo isn’t the fastest external drive out there, but still this seems strange. When I daisy chain two old WD MyBooks via a FW800 to FW400 cable to my Drobo, the old WD’s are a LOT faster compared to the Drobo when running benchmarks (if I understand the test info right of course).

The WD’s are empty though and the Drobo is 60% filled.

But another thing I noticed was that the WD’s were formatted with FAT32 while the Drobo is formatted with OS X journaled. For the fun of it I tried to format a WD into OS X journaled and BAAAMMM it was suddenly a lot slower than the Drobo. I did not know that the file system mattered THAT much?

I have attached an image to illustrate my problem.

http://cl.ly/2h2U3R3q0W0a3C0M0519

Thanks for adding any info to this :slight_smile:

R.I.P. Steve Jobs

What makes you think that speed of the drive depends on the interface speed only? A highway ALLOWS you to drive a fast car if you have one, not GUARANTEES that you’ll reach 150 mph on a moped, right?. Filestystem type doesn’t have much to do with that in this particular situation either.

To sum this up - it only means that Drobo doesn’t even saturate FW400 and that is indeed the case.

It seems counter-intuitive, but it’s one of those things that’s ‘always been that way’.

FATx is faster than NTFS and HFS+ on small volumes with low used space.

That trend rapidly reverses when:

The FATx volume begins to fill or the volume is larger than 160GB.

NTFS and HFS+ are MUCH faster than FATx when the volume size is large (160GB+) or the filesystem becomes more populated.

I would suspect in your test, you got those weird results because the Drobo is not an inherently fast device to begin with, it’s 60% full and it’s chained with FW400 devices. I know the FW spec says chaining doesn’t have any impact on transfer speeds, but, at least when it involves the Drobo, I have noticed a pretty big difference.

FW chaining on a FW800 interface isn’t supposed to affect performance (on a FW400 interface it definitely does) as the interface is supposed to be able to “partition” the bandwidth intelligently somehow. There’s a term that’s not coming to mind…
Assuming, of course, the wide pipe is at the interface end and not being bottlenecked by a narrower pipe upstream. :slight_smile:

But of course “in theory” and “in practice” often don’t jive.

mgriffin34’s right - FAT is faster for smaller volumes, but beyond a certain size, it gets bogged down.
Journaled filesystems like NTFS and HFS+ are more tolerant about incomplete operations.

Thanks a lot… Did not know that much about Fat32, so I feel much clever now :)[hr]
Tried to attach the FW400 WD’s directly to the iMac and they went back to almost “FAT32” speed again.