Daniel Nashed's Blog

Keep your File-System Size below 2 TB

There is a not very well known issue that if you have Solaris and ZFS you can run into trouble when you grow your file-system above 2 TB.
In that case your FT indexes do not work any more because the OS returns an error ("Unknown OS error").

There is a SPR #KBRN7DZNJW and a hotfix available for the problem. But the better idea is to not grow your file-systems above a certain limit.
Normally 500 GB would be a good size that you can still handle. And you should always have at least 20-30% free space at a minimum to allow the file-system to operate smoothly (fragmentation etc).

If you grow your file-systems too big you run into all sorts of problem which cause administrative and performance issues.
E.g. your backup time exceeds 12 or even 24 hours ... Performance impact etc.

Specially on Linux, AIX and Solaris adding more file-systems is very easy by mounting them into the root file-system tree.
On Windows you can use junctions which have a couple of limitations which can be worked around.

So this is a prominent example where large file-systems can cause issue. Also on Windows 2 TB is the magical number.

I would always stay way below 2 TB. Better if you can keep file-systems below 500 GB and also spread them on multiple RAIDs or SAN LUNs...

-- Daniel

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