Data Recovery Weekly

There is a set of questions which customers seem to be repeating perpetually, We have a large fancy storage system which failed. Can we fix it in place, without copying data? No, you can not. You absolutely have to copy the data away. Yes, this means purchasing the disk set of the same size. Yes we know full well that it is 50TB, meaning 13x 4Tb drives. Yes, plus a RAID controller for it. Can we have a RAID5 recovered when two disks failed? No, that won't work. OK if we can get the RAID recovered, maybe we can just get 2/3rds of files, since we'are only missing a little bit?  No,  that won't work either, because any file lager than block size will be broken. So we still can get some small files? There are surprisingly few useful small files when the value of small is defined by the RAID controller. OK maybe we can get our Word/Excel files and repair them using whatever DOC/XLS repair tool? No, that won't work. The data is missing, and when the data...

This is a short list compiled based on the tech support experience,without much explanation Avoid USB-to-SATA converters (for bad reliability); Marvell chipsets (for bad handling of bad sectors); Silicon Image controllers or any RAID cards based on these (after SIL_QUIRK_MOD15WRITE; even if SIL_QUIRK_MOD15WRITE does not apply to your controller, this is not an excuse to use Sil); nVidia chipsets (for bad reliability of disk controllers under load)

Been answering a support query recently, and mentioned to client that USB is outright bad in all respects [for data recovery use]. Well, pretty much so, if one of the drives has a bad block, quite likely the USB converter will lock up on hitting that block; with USB 2.0, speed is 15 MB/sec maximum, for all drives combined, even if you have what appears to be different ports, they will be routed through a same root port or hub anyway; devices advertised as USB 3.0 often work at 2.0 speeds, with no warning whatsoever; power supply issues and limitations are difficult to control,  especially so if hubs are involved; any setup with daisy-chained hubs is unstable, especially so with USB 3.0; So, think twice before starting a recovery with a laptop-based all-USB setup.

Once in a while people demand that we provide technical support not only by e-mails, but by phone as well. Despite the apparent reasonableness of the request, it is not that simple in practice. A typical case of technical data recovery support via email looks like the following:   A client contacts our technical support and describes his or her problem for the first time.   We send a reply where we ask the questions to clarify obscure points. Usually we have three to five questions (although there may be more) which are organized as a numbered list. In the following email a client answers the questions. There are cases when client needs time to think or do some simple checks to answer the questions. In response to the message from a client, we send a list of recommended actions or step-by-step instructions as to what he or she should do next. There are cases when boilerplate instructions fit just right; however, almost half of all cases require pondering on o...