Flashcache + Ramdisk?

Hello all,

Setting up flashcache and using ramdisk as the cache disk to speed up my /var partition. So far work great, got significant IO improvements especially the iops.

For the ramdisk size I set it to 2GB and the flashcache cache mode is using write-through (safest).

[root@server ~]# dmsetup table
var_cache: 0 5684107264 flashcache conf:
        ssd dev (/dev/ram0), disk dev (/dev/md2) cache mode(WRITE_THROUGH)
        capacity(1952M), associativity(512), data block size(4K)
        disk assoc(256K)
        skip sequential thresh(0K)
        total blocks(499712), cached blocks(462876), cache percent(92)
        nr_queued(0)
Size Hist: 1024:1 4096:8310442

Simple bencmark using ioping:

[root@server ~]# ioping -c 10 /var
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=1 time=12 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=2 time=21 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=3 time=21 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=4 time=21 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=5 time=21 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=6 time=21 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=7 time=21 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=8 time=21 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=9 time=20 us
4.0 KiB from /var (ext4 /dev/mapper/var_cache): request=10 time=20 us

--- /var (ext4 /dev/mapper/var_cache) ioping statistics ---
10 requests completed in 9.0 s, 50.3 k iops, 196.3 MiB/s
min/avg/max/mdev = 12 us / 19 us / 21 us / 2 us

[root@server ~]# ioping -RD /var

--- /var (ext4 /dev/mapper/var_cache) ioping statistics ---
218.9 k requests completed in 3.0 s, 214.1 k iops, 836.2 MiB/s
min/avg/max/mdev = 3 us / 4 us / 25 us / 0 us

[root@server ~]# ioping -RL /var

--- /var (ext4 /dev/mapper/var_cache) ioping statistics ---
18.1 k requests completed in 3.0 s, 6.7 k iops, 1.6 GiB/s
min/avg/max/mdev = 143 us / 150 us / 454 us / 4 us

[root@server ~]# ioping -RC /var

--- /var (ext4 /dev/mapper/var_cache) ioping statistics ---
5.0 M requests completed in 3.0 s, 1.8 M iops, 7.1 GiB/s
min/avg/max/mdev = 0 us / 0 us / 53 us / 0 us

Any one using this kind of solutions?

http://ift.tt/1dvHQ0Z