Evan Hoffman's silly writings. » nilfs http://www.evanhoffman.com/evan When 3-nines uptime is just way too much. Mon, 06 Sep 2010 00:36:39 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 NILFS – A File system to make SSDs scream… in pain? http://www.evanhoffman.com/evan/2009/10/27/nilfs-a-file-system-to-make-ssds-scream-in-pain/ http://www.evanhoffman.com/evan/2009/10/27/nilfs-a-file-system-to-make-ssds-scream-in-pain/#comments Tue, 27 Oct 2009 21:05:12 +0000 evan http://www.evanhoffman.com/evan/?p=188 So I got this 128 gig Corsair SSD and put it in my laptop at work. After some fiddling I copied my old disk over to my new disk by booting to Knoppix and doing dd if=/dev/sda of=/dev/sdb bs=4k conv=notrunc,noerror. It’s a lot faster, but what’s really fast now is my Windows XP VM. Anyway, I was looking into other filesystems to try out on SSD to improve speed and I found this article claiming that NILFS is the best choice. So I decided to test it using the same ghetto test I always use for filesystem performance: dd!

Drive info:

Model: ATA CORSAIR CMFSSD-1 (scsi)
Disk /dev/sda: 128GB

The nilfs version in use is whatever’s in yum:

[root@ehoffman ~]# rpm -qai nilfs-utils
Name        : nilfs-utils                  Relocations: (not relocatable)
Version     : 2.0.14                            Vendor: Fedora Project
Release     : 2.fc11                        Build Date: Thu 30 Jul 2009 07:16:08 PM EDT
Install Date: Tue 27 Oct 2009 04:18:28 PM EDT      Build Host: xenbuilder4.fedora.phx.redhat.com
Group       : System Environment/Base       Source RPM: nilfs-utils-2.0.14-2.fc11.src.rpm
Size        : 211949                           License: GPLv2+
Signature   : RSA/8, Thu 30 Jul 2009 09:25:18 PM EDT, Key ID 1dc5c758d22e77f2
Packager    : Fedora Project
URL         : http://www.nilfs.org
Summary     : Utilities for managing NILFS v2 filesystems
Description :
Userspace utilities for creating and mounting NILFS v2 filesystems.

NILFS volume on /dev/sda9, ext3 on /dev/sda8

/dev/sda8 on /docs type ext3 (rw)
/dev/sda9 on /nilfs type nilfs2 (rw,gcpid=3711)

I found this pretty unsettling when I mounted the nilfs volume:

[root@ehoffman ~]# mount -t nilfs2 /dev/sda9 /nilfs/
mount.nilfs2: WARNING! - The NILFS on-disk format may change at any time.
mount.nilfs2: WARNING! - Do not place critical data on a NILFS filesystem.

Write a 100 MB file and a 1.0 GB file to the nilfs volume and the ext3 volume:

[root@ehoffman ~]# dd if=/dev/zero of=/docs/zeros.dat bs=4k count=25600
25600+0 records in
25600+0 records out
104857600 bytes (105 MB) copied, 0.434741 s, 241 MB/s
[root@ehoffman ~]# rm -f /docs/zeros.dat
[root@ehoffman ~]# dd if=/dev/zero of=/docs/zeros.dat bs=4k count=256000
256000+0 records in
256000+0 records out
1048576000 bytes (1.0 GB) copied, 19.6931 s, 53.2 MB/s
[root@ehoffman ~]# rm -f /docs/zeros.dat
[root@ehoffman ~]# dd if=/dev/zero of=/docs/zeros.dat bs=4k count=256000
256000+0 records in
256000+0 records out
1048576000 bytes (1.0 GB) copied, 12.7625 s, 82.2 MB/s
[root@ehoffman ~]# rm -f /docs/zeros.dat
[root@ehoffman ~]# dd if=/dev/zero of=/nilfs/zeros.dat bs=4k count=25600
25600+0 records in
25600+0 records out
104857600 bytes (105 MB) copied, 5.42617 s, 19.3 MB/s
[root@ehoffman ~]# dd if=/dev/zero of=/nilfs/zeros.dat bs=4k count=256000
256000+0 records in
256000+0 records out
1048576000 bytes (1.0 GB) copied, 47.4966 s, 22.1 MB/s
[root@ehoffman ~]# rm -f /nilfs/zeros.dat

With 100 MB, ext3 writes at 200+MB/s and with 1 gig it writes around 50+ MB/s. I think the SATA controller on my laptop is SATA I (not SATA II). On nilfs it seems to hover around 20-25 MB regardless of file size. Anyway, based on this I guess I’ll be staying with ext3/4 for the foreseeable future.

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