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Catastrophically low write speed on encrypter RAID volume

Topics: Technical Issues
Dec 5, 2016 at 3:52 AM
Edited Dec 10, 2016 at 9:04 AM
Computer: RAID6 of 8 HDDs (Hitachi HUA723030...) on 3ware 9650SE-12ML controller on Intel P55-based Mobo with Core i5-661 CPU (hardware AES acceleration to 2.4GB/s R/W). Latest officially available firmware and drivers with Win7 OS. RAID status is OK (no background init).

Problem: any encrypted volume or a file container maden with Veracrypt (1.19/1.17) and TrueCrypt 7.1a on this RAID shows catastrophically LOW WRITING speed. Originally R/W speed is 500/400MB/s on non-encrypted RAID-volume, but only 3-5MB/s write speed is on the encrypted one. While the read speed is almost OK (it is lower but not dramatically). Checked with ATTO Benchmark and direct file copying. Encrypted with ONLY AES algo, which is hardware accelerated by CPU to >2GB/s. File systems - NTFS and exFAT, no matter (3MB/s on NTFS and 5MB/s on exFAT).

Similar bug is if we relace Hitachi HDDs with Seagate HDDs (for RAID0, 5 and even a Single drive connected to 3ware!!!)

A single drive (ST4000NM) in the same PC (connected to P55 chipset) shows about OK speed on encrypted container (twice lower only on small blocks 512B-4KB).

What's wrong with the bundle (VeraCrypt vs 3ware RAID)?

BTW, RAIDs of the same HDDs on LSI 9260 showed normal speed of encrypted volume, but LSI card is gone...
Dec 10, 2016 at 9:05 AM
Edited Dec 10, 2016 at 9:07 AM
Apparently, there is a conflict of the 'chunk size' in caching/operating policy of VeraCrypt and 3ware 9650SE. Since 3ware stopped the suppot, it would be great if the VeraCrypt developer make some options in the next version to try to resolve the conflict.

Partially the problem could be resolved if set the SaveStor Policy of the 3ware 9650SE from default Balanced to Performance, but there are speed issues still (sufficient read speed drops), and it's not safe for data to loss...
Dec 12, 2016 at 5:22 PM
Edited Dec 12, 2016 at 5:23 PM
BTW, the volume encrypted with the DiskCryptor 1.1.846.118 shows NORMAL speed in the system, while volumes made with ChiperShed, GOSTCrypt, and Exlade Cryptic Disk show the same very low speed like VeraCrypt (all coded with AES only, except the GOSTcrypt).

So the problem of the incompatibility 3ware 9650SE with the VeraCrypt etc. encryption is followed from the TrueCrypt engine and should be fixed there.

Does anybody knows, is the DiskCryptor less reliable than VeraCrypt and why, if so?
Dec 12, 2016 at 7:13 PM
I do not know about DiskCryptor audit.

I looked at sources. It is simpler but faster. It does not support containers in file.

Optimization is one of the way to improve VeraCrypt. Too much directions of work :)
Dec 14, 2016 at 5:37 PM
Edited Dec 14, 2016 at 5:40 PM
Many thanks for your work! :)
The DiskCryptor has one essential feature that allows it to work with RAID much faster - "Support for disk devices with large sector size (important for hardware RAID operation)." (see https://diskcryptor.net/wiki/Main_Page)
I suppose that it's important to VeraCrypt to get the same optimization to get no problem with RAID operations. Typical chunk size for RAID massives is now 256KB (it can be varied from 64 to 1024KB). I guess this is the key why VC dramatically lowers the write speed on RAIDs.