On Wed, Apr 8, 2015 at 9:02 PM, Kai Krakow <kai@xxxxxxxxxxx> wrote: > arnaud gaboury <arnaud.gaboury@xxxxxxxxx> schrieb: > >> I plan to setup Bcache on Btrfs SSD/HD caching/backing device. The >> box will be a server, but not a production one. >> >> I know this scheme is not recommended and can be a cause of filesystem >> corruption. But as I like living on the edge, I want to give a try, >> with a tight backup policy. >> >> Any advice? Any settings that could be worth to avoid future drama? > > See my recommendations about partitioning here I just posted: > http://permalink.gmane.org/gmane.linux.kernel.bcache.devel/2865 > > Take care of the warnings about trimming/enabling discard. I'd at least test > it if you want to use it before trusting your kitty to it. ;-) > > BTW: I'm planning on a similar system tho the plans may well be 1 or 2 years > in the future and the system is planned to be based off bcache/btrfs. It > should become a production container-VM host. We'll see. Fallback plan is to > use a battery-backed RAID controller with CacheCade (SSDs as volume cache). > > -- > Replies to list only preferred. Thank you. Here is what I did to prevent any drama: the caching device, a SSD: - GPT partitions. ------------------------------------------------------- # gisk /dev/sdd Command: p Disk /dev/sdb: 224674128 sectors, 107.1 GiB Logical sector size: 512 bytes Disk identifier (GUID): EAAC52BC-8236-483F-9875-744AF7031E72 Partition table holds up to 128 entries First usable sector is 34, last usable sector is 224674094 Partitions will be aligned on 2048-sector boundaries Total free space is 2014 sectors (1007.0 KiB) Number Start (sector) End (sector) Size Code Name 1 2048 167774207 80.0 GiB 8300 poppy-root 2 167774208 224674094 27.1 GiB 8300 poppy-cache --------------------------------------------------------------------------------------- Then : # make-bcache --wipe-bcache --block 4k --bucket 2M -B /dev/sdd4 -C /dev/sdb2 --discard Now, when referring to your post, I have no idea about: Fourth - wear-levelling reservation. Shall I change my partition table for /dev/sdd2 and leave some space? Below are some infos about the SSD: ----------------------------------------------------------------------------------------- # hdparm -I /dev/sdb /dev/sdb: ATA device, with non-removable media Model Number: OCZ-VERTEX2 3.5 Serial Number: OCZ-52181PZL67XEETUZ Firmware Revision: 1.33 Transport: Serial Standards: Used: unknown (minor revision code 0x0028) Supported: 8 7 6 5 Likely used: 8 Configuration: Logical max current cylinders 16383 16383 heads 16 16 sectors/track 63 63 -- CHS current addressable sectors: 16514064 LBA user addressable sectors: 224674128 LBA48 user addressable sectors: 224674128 Logical Sector size: 512 bytes Physical Sector size: 512 bytes Logical Sector-0 offset: 0 bytes device size with M = 1024*1024: 109704 MBytes device size with M = 1000*1000: 115033 MBytes (115 GB) cache/buffer size = unknown Nominal Media Rotation Rate: Solid State Device Capabilities: LBA, IORDY(can be disabled) Queue depth: 32 Standby timer values: spec'd by Standard, no device specific minimum R/W multiple sector transfer: Max = 16 Current = 16 DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6 Cycle time: min=120ns recommended=120ns PIO: pio0 pio1 pio2 pio3 pio4 Cycle time: no flow control=120ns IORDY flow control=120ns ------------------------------------------------------------------------------------------------- -- google.com/+arnaudgabourygabx -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
