On Feb 02, 2007 10:25 -0800, Lin Shen (lshen) wrote: > Could you explain a bit more how the number 400M was decided? Ext3 > itself won't need that much disk space, right? Also, is this number > related to the total capacity of the Luster filesystem? In other words, > will the MDS always need 400M to work properly for a filesystem of size > 1T or just 1G? By switching to a different underline filesystem (i.e., > from ext3 to ext2), can this number be lowered?
In fact you do NOT need the full 400MB of journal space, and lconf will not create a journal that large if you have a smaller filesystem. The default size of the journal is: - device size < 1GB => use default mke2fs, 16MB - 1GB < device size < 10GB => use device size / 25 - device size > 10GB => use 400MB > This is important to us. Since we may have a use case that runs Luster > on a 1G Compact Flash (to be shared among a few nodes). Does this mean > that only a little more than half of the capacity can be used for data? No, nothing of the sort. Ext3 can have a journal as small as 4MB, regardless of the device size. The only drawback is a potential reduction in performance when there are many clients. In a small setup like yours it may not make much difference at all. > > -----Original Message----- > > From: Andreas Dilger [mailto:[EMAIL PROTECTED] > > Sent: Monday, January 29, 2007 7:04 PM > > To: Lin Shen (lshen) > > Cc: [email protected] > > Subject: Re: [Lustre-discuss] disk space needed to run MDS > > > > On Jan 29, 2007 12:25 -0800, Lin Shen (lshen) wrote: > > > I read once in the alias that running MDS requires a minimum disk > > > space of 400MB + 4kB * number of files. Is this still the > > case with 1.6beta? > > > > Yes. This relates more to ext3 than to Lustre. > > > > Cheers, Andreas > > -- > > Andreas Dilger > > Principal Software Engineer > > Cluster File Systems, Inc. > > Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. _______________________________________________ Lustre-discuss mailing list [email protected] https://mail.clusterfs.com/mailman/listinfo/lustre-discuss
