[Fwd: Re: Show stopper for large disks with 5.4-RELEASE]

secmgr security at jim-liesl.org
Wed Jun 8 21:50:11 GMT 2005

Dmitriy Kirhlarov wrote:

>Hi Pierre!
>On Wed, 08 Jun 2005, Pierre DAVID wrote:
>>Do you have a clue to help us use FreeBSD and not switch on Linux
>>for this service?
>Bad workaround.
>You can create many small partitions and mount_unionfs.
Actually it's a very valid choice.  At this time, Linux offers ext3, XFS 
(from SGI), JFS (from IBM) and RieserFS as journaled file systems (as in 
no fscking fsck).  JFS, XFS and RieserFS offer very good performance 
with big directories (like Maildir style mailboxes could create) and 
recover from unexpected outages quickly (journal replay to last 
checkpoint is typically seconds) and robustly.  In fact, if I were to 
deploy a large Maildir system, where users could have thousands of files 
per directory, I would definitly be looking at JFS, XFS or Rieser.  
Linux also has a WORKING logical volume manager, and a WORKING s/w raid5 
whose performance is close to all but the most high end RAID 
controllers. But I digress.

I really like FreeBSD for a lot of things, but outside of snap and 
union, storage and filesystems are pretty much SOTA circa 1998

I'm not that amazed by his numbers.  on a 5.3R system, when I use snap 
to freeze a dump of a 13% used 140 gb gmirror partition, the system 
(2ghz AMD, SATA150 drives) goes out to lunch for about 45 seconds, 
hanging all IO's to the partition.  Scale that upto 1.8TB, and I could 
see where you could be going nowhere for a good 10 minutes just waiting 
for the snap to finish.  Still better than waiting hours for fsck, but 
nowhere near the recovery speed of a true journaled system.


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