- Thread Starter
- #26
Further experiments with compression. I had to migrate my database drives (running low on space AGAIN) so I thought I'd go all out and try:
1. Block size of 1M
2. Compression of gzip-7 (default gzip compression is gzip-6)
Now the migration is complete, the difference in allocated space is substantial (see the ALLOC field)
And compression ratio:
As a gentle test I had set compression to gzip-7 a week or so before the migration, and apart from higher CPU usage, did not see any real impact on performance, so I decided to stick with it when migrating. This is on a MySQL server with a lots of random accesses to small bites of large datasets, so gzip compression taking 2 times (or whatever) longer than lz4 is less relevant when I/O wait times are usually the bottleneck. YMMV.
1. Block size of 1M
2. Compression of gzip-7 (default gzip compression is gzip-6)
Now the migration is complete, the difference in allocated space is substantial (see the ALLOC field)
Code:
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
db 10.9T 1.32T 9.56T - - 2% 12% 1.00x ONLINE -
db_OLD 2.72T 1.85T 893G - - 56% 67% 1.00x ONLINE -And compression ratio:
Code:
NAME PROPERTY VALUE SOURCE
db compressratio 2.91x -
db_OLD compressratio 2.05x -As a gentle test I had set compression to gzip-7 a week or so before the migration, and apart from higher CPU usage, did not see any real impact on performance, so I decided to stick with it when migrating. This is on a MySQL server with a lots of random accesses to small bites of large datasets, so gzip compression taking 2 times (or whatever) longer than lz4 is less relevant when I/O wait times are usually the bottleneck. YMMV.