Comment by Felger | Hacker News Reader

Comment by Felger | Hacker News Reader

Parent Full thread

A very useful use case discovered no later than last week : local dedup management by Synology C2 Backup Agent and TBW on the OS SSD.

C2 Backup agent stores dedup/chunks data by default in ProgramData, which is stored on C:... which is usually a SSD nowadays.

I noticed a 3:4 ratio between written data in local dedup folder vs uploaded data volume on the remote C2 5 TB storage (suscribed a C2 Business).

TBW grew indeed horrifyingly fast on the SSD, and I estimated it would completely wear it in about a year or so, with the 2 TB and growing data to backup with my standard retention scheme.

So I made a 32 GB (16 GB was not enough peak size) lmDisk ramdisk with backup/restore at shutdown/startup (it is featured by lmDisk and quite nicely), mounted in place of the dedup folder, and ran my tasks.

poof, reduced TBW on SSD by 99%.

(4x16 GB DDR4 ECC Reg on my server, so not concerned about memory errors)

I think the question was more tuned to physical ram disks, but I'm not sure.

Either way, how many terabytes were being written each day? And how much can your drive take? It looks like I could go pay $60 right now for 600TB of endurance, and $35 for 200TB of endurance. If you already have the extra ram than go for it but it doesn't seem like a setup to make on purpose.

Maybe your backup system has far more writes than mine? I have terabytes of backups but the average written for each daily backup is about 10GB.

(I was answering to the previous comment wondering if ramdisks still have any interesting usage nowadays.)

About 150 TBW endurance on a 250 GB Samsung M.2 NVMe Evo 970+. On paper that is, but since it is the OS SSD with Windows Server 2022 STD (sole DC AD/DHCP/DNS/Hyper-V), in production, I won't take any risk. RAID 1 in this scenario would have changed nothing. On the side, I have 40 TB RAID10 for storage.

So I cancelled the first C2 exec (with C2 encrypt on) when I reached 195 TBW on the SSD. Monitoring the ramdisk use still shows about 3:4 ratio on complete snapshot.

I have about 1 million files on the 2,29 TB data to backup.

I had indeed the RAM sticks available for free, simply had to take them (2x16 GB ) from a decomissioned ML350 Gen9 (which uses DDR4-2133P ECC Reg). It now serves me as a bench, litterally.

Unless that server replaces a quarter of those files every day, the lesson I'm getting here is "Don't use C2 Backup agent".

Reply on news.ycombinator.com