On Sat, Sep 29, 2012 at 12:02:23AM +0600, Roman Mamedov wrote: > On Fri, 28 Sep 2012 18:44:07 +0200 > Goffredo Baroncelli <kreij...@inwind.it> wrote: > > > This means that the ration of space physically allocated on the disk and > > the space available is 7GB/10GB = 0.7 . So on 135GB of disk, only 94GB > > are available. > > You assume metadata allocation will always grow linearly with data, which is > not true. So in my opinion it is not a good estimate.
No, but it's the best model we have right now. (And probably about the best model we will have, without knowledge of the future intentions of the user). Without inlining file data, the metadata is dominated by checksums, which is a linear relationship (approx 1000:1). With inlining file data, metadata is probably dominated by inline data; assuming the ratio of small-to-large files on the FS remains unchanged in future, a linear relationship also applies. For general usage, I'm happy to assume that the current ratio of data to metadata will remain largely unchanged over the lifetime of the FS. > > > Why use underscores instead of spaces? > > > > Simplify the parsing in scripts > > I think it looks awkward and is not warranted since this is a primarily > user-facing utility. Also none of the other similar tools shy from having > spaces anywhere they need to, e.g. > > # mdadm --detail /dev/md0 > /dev/md0: > Version : 1.2 > Creation Time : Wed May 25 00:07:38 2011 > Raid Level : raid5 > Array Size : 3907003136 (3726.01 GiB 4000.77 GB) > Used Dev Size : 976750784 (931.50 GiB 1000.19 GB) > Raid Devices : 5 > Total Devices : 5 > Persistence : Superblock is persistent > > Intent Bitmap : Internal > > Update Time : Fri Sep 28 21:20:51 2012 > State : active > Active Devices : 5 > Working Devices : 5 > Failed Devices : 0 > Spare Devices : 0 > > Layout : left-symmetric > Chunk Size : 64K > > Name : avdeb:0 (local to host avdeb) > UUID : b99961fb:ed1f76c8:ec2dad31:6db45332 > Events : 14254 > > Number Major Minor RaidDevice State > 7 8 17 0 active sync /dev/sdb1 > 6 8 33 1 active sync /dev/sdc1 > 3 8 65 2 active sync /dev/sde1 > 4 8 49 3 active sync /dev/sdd1 > 5 8 81 4 active sync /dev/sdf1 > > # lvdisplay > --- Logical volume --- > LV Path /dev/alpha/lv1 > LV Name lv1 > VG Name alpha > LV UUID HP19fU-oMhM-sdqN-yFWa-N3Rs-ktBw-21GSD2 > LV Write Access read/write > LV Creation host, time , > LV Status available > # open 0 > LV Size 3.52 TiB > Current LE 115431 > Segments 3 > Allocation inherit > Read ahead sectors auto > - currently set to 4096 > Block device 252:0 ... and I've always found those hard to deal with in scripts. :) (But they do have "plumbing" options, to use the git terminology, so I'd be happy with having a parsable output option). Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Hey, Virtual Memory! Now I can have a *really big* ramdisk! ---
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