Re: [zfs-discuss] raidz and compression, difficulties
On Sat, 26 Jan 2008 23:33:16 +0100, Toby Thain [EMAIL PROTECTED] wrote: On 26-Jan-08, at 2:24 AM, Joachim Pihl wrote: So far so good, zfs get all reports compression to be active. Now for the problem: After adding another 300GB of uncompressed .tif and .bin/.cue (audio CD) files, I wouldn't expect very much compression on that kind of data. I didn't expect miracles, but since WinRAR gave 13% compression on a representative data set with ZIP compression at the fastest setting, I was expecting to see a compression ratio 1.05 at least, not == 1.00. Getting 5-10% more space on a drive never hurts. Could it be that I should specify compression algorithm? Documentation says it will use lzjb by default, so I did not set it explicitly. -- Joachim Hvorfor bruke fremmedord, når det finnes adekvate norske substitutter? ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] NFS performance on ZFS vs UFS
I also test the nfs with 'zfs set sharenfs=on' performance with a linux client. By echo zil_disable/W0t1 | mdb -kw the small files from nfs speed up 10x. about zil_disable,see Eric Kustarz's blog: http://blogs.sun.com/erickustarz/entry/zil_disable This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] raidz and compression, difficulties
I didn't expect miracles, but since WinRAR gave 13% compression ZFS doesn't compress a block if it can't get a certain amount of return on it. Since the default compression is less effective than RAR, you can bet ZFS is seeing much less than 13% return. I expect everything is working properly, and you are just dealing with well-compressed files :) You could try setting the zfs compression to a stronger algorithm to see if anything gets compressed that way. This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] raidz and compression, difficulties
Why not create a sample dataset and throw some large .txt files out there and see what happens? That way you'll know for certain if there's some bug you're hitting, or if it's just not applicable to your current dataset. On 1/27/08, Joachim Pihl [EMAIL PROTECTED] wrote: On Sat, 26 Jan 2008 23:33:16 +0100, Toby Thain [EMAIL PROTECTED] wrote: On 26-Jan-08, at 2:24 AM, Joachim Pihl wrote: So far so good, zfs get all reports compression to be active. Now for the problem: After adding another 300GB of uncompressed .tif and .bin/.cue (audio CD) files, I wouldn't expect very much compression on that kind of data. I didn't expect miracles, but since WinRAR gave 13% compression on a representative data set with ZIP compression at the fastest setting, I was expecting to see a compression ratio 1.05 at least, not == 1.00. Getting 5-10% more space on a drive never hurts. Could it be that I should specify compression algorithm? Documentation says it will use lzjb by default, so I did not set it explicitly. -- Joachim Hvorfor bruke fremmedord, når det finnes adekvate norske substitutter? ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] raidz and compression, difficulties
On Sun, 27 Jan 2008 19:11:33 +0100, MC [EMAIL PROTECTED] wrote: I didn't expect miracles, but since WinRAR gave 13% compression ZFS doesn't compress a block if it can't get a certain amount of return on it. Since the default compression is less effective than RAR, you can bet ZFS is seeing much less than 13% return. What is the threshold, does anyone know that? It sound like a fair decision, though. Try to compress on write, increase perrformance on read by not compressing if there is little space to be gained. Wouldn't slow down writes compared to not having such a threshold either. Clever! I expect everything is working properly, and you are just dealing with well-compressed files :) Raw audio and uncompressed 16bit TIFF files (35mm negative scans) have high content entropy, so they are difficult to compress, that could be the culprit. You could try setting the zfs compression to a stronger algorithm to see if anything gets compressed that way. -- Joachim Hvorfor bruke fremmedord, når det finnes adekvate norske substitutter? ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] raidz and compression, difficulties
Joachim Pihl wrote: On Sun, 27 Jan 2008 19:11:33 +0100, MC [EMAIL PROTECTED] wrote: I didn't expect miracles, but since WinRAR gave 13% compression ZFS doesn't compress a block if it can't get a certain amount of return on it. Since the default compression is less effective than RAR, you can bet ZFS is seeing much less than 13% return. What is the threshold, does anyone know that? It sound like a fair decision, though. Try to compress on write, increase perrformance on read by not compressing if there is little space to be gained. Wouldn't slow down writes compared to not having such a threshold either. Clever! See line 108 of this file: http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/fs/zfs/zio_compress.c#73 -- Darren J Moffat ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
