RAID5 Recovery time

Discussions on using the professional data recovery program R-STUDIO for RAID re-construction, NAS recovery, and recovery of various disk and volume managers: Windows storage spaces, Apple volumes, and Linux Logical Volume Manager.
d533wf

RAID5 Recovery time

Post by d533wf » Wed Feb 17, 2016 10:45 am

Firstly I should say that I am very impressed with R-studio. It has done a fantastic job at recovering my 4 disc RAID 5 array (1 disk missing). I have an external RAID controller box but after switching in a new blank disk it will not recognise the disks so I've had to recover it manually.

My question is about recovery time. I have 5.7TB of data which is spread over my 3x3TB working drives. I need to recover all of this data. My drives are connected using SATA-USB cables as I don't have 3 spare internal SATA connections. The RAID block size is 512 bytes.

Currently my files are being recovered at just under 1Mb/s which is going to take a LONG time! Now obviously if this is the only option then I'll just have to wait, but I was just curious as to whether I can improve the speed of this?

Thanks!
Tim

Alt
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Re: RAID5 Recovery time

Post by Alt » Thu Feb 18, 2016 9:05 am

The main bottleneck for R-Studio is the disk access rate of the system. Do you use USB 2 or 3 adapters? And are the disk connected to the same USB port (through a coupler)?
Are you scanning the RAID or copying recovered files?

d533wf

Re: RAID5 Recovery time

Post by d533wf » Thu Feb 18, 2016 9:19 am

USB2 unfortunately (I only have 1 USB3 port) but different ports.

I am copying my recovered files using the 'Recover' tool.

One idea I had was to image the disks first onto my internal hard drives if there is space to increase transfer speed. Is recovering from disk images faster/slower than from (fully working -not failing) hard drives?

Also do you know the typical size reduction for a disk image compared to a physical disk (e.g. how big is a compressed image of a 3Tb hard drive likely to be?)

Corsari
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Re: RAID5 Recovery time

Post by Corsari » Thu Feb 18, 2016 10:57 am

Another factor is the average files size
The smallest they are the longer will be the time required to open/close the files in relation to the copy speed.

E.G. We are copying the content of an HP MSA 60 S.A.N. from Genreral Electric Healthcare Systems, composed of 12 drives 1TB each in RAID 6 with 2 missing drives (here it come in the game, partially, the calculation needed for the Q) we have reconstructed past week. Luckily it was filled with "only" 6TB of data, but those medical images are sets made of the image + a small set of description files.

This drops the copy speed to an Average of 4MB/sec

This turns in 330/360 GB/day

Which will end in a copy period time of something less of 20 days :-)

UPS for everything and crossed fingers
Robert
Technical Manager @ Recupero Dati RAID FAsTec (Italy)

USEFUL RULES and GUIDELINES
1) What to check BEFORE begin a disk image/clone process [link]
2) Disks that are too slow while imaging/cloning them [link]
3) All my posts on this forum [link]

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Re: RAID5 Recovery time

Post by Alt » Fri Feb 19, 2016 9:31 am

d533wf wrote:USB2 unfortunately (I only have 1 USB3 port) but different ports.

I am copying my recovered files using the 'Recover' tool.

One idea I had was to image the disks first onto my internal hard drives if there is space to increase transfer speed. Is recovering from disk images faster/slower than from (fully working -not failing) hard drives?

Also do you know the typical size reduction for a disk image compared to a physical disk (e.g. how big is a compressed image of a 3Tb hard drive likely to be?)
I think you'd better leave all as it is and let the files be copied.
But if you had created disk images through the USB3 port/adapter, you'd have spent less time. Compression ratio depends on many things, types of files stored on the disk being the main factor. If they are of compressed types, like jpg, the ratio will be small.

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