[Date Prev][Date Next][Subject Prev][Subject Next][ Date Index][ Subject Index]

Re: Backup--OT

At 22/04/2014 16:21, you wrote:


Harry, I think you're right to worry about mirroring primarily the c:\
volume. (I don't know this for a fact but I would assume that as long as
you had that volume, you would always be able to get a bootable system.)
Your plan does seem to offer a high degree of security.  My primary
concern is that I am suspicious of software RAID, which I have never
used. My gut instinct is that RAID should be handled in hardware. Of
course the only way to find out how well it's going to work is to try it,
and I certainly will be interested to hear your experiences.


Regarding physical failure of SSDs, this is my understanding of how it is
supposed to work on recent SSDs: that  a sector which may
become un-writable will yet remain readable, thus insuring against loss
of data. Whether this always happens according to plan is another
question. Of course there are all kinds of other problems with SSDs,
including, as you will have read, catastrophes that can result from
unintentional shutoff (unlikely with a laptop, which acts as its own UPS
when connected to AC). Nevertheless, I have had vastly fewer system
problems since switching to SSDs four or five years ago. SSDs have
saved me days of downtime.


Regarding boot speed (and overall speed) of USB3 externals, my LaCie
informant says 'As long as the USB 3.0 drive supports UASP (LaCie does,
as well as all USB 3.0 drives sold by the Apple Store, a requirement). If
a drive does not support UASP, it will be slower on USB 3.0.'


So what is UASP? See
https://en.wikipedia.org/wiki/USB_Attached_SCSI; eudora="autourl">
https://en.wikipedia.org/wiki/USB_Attached_SCSI


Regarding your backup strategies in general, you have not mentioned what
you are doing (other than DropBox) about off-site backup. What about your
system backup? Assuming a good RAID-1 controller, the following has been
suggested: Have a RAID 1 system with two drives, and have a third,
identical drive. Week 1: Remove disk 2 from the RAID and insert the blank
disk 3. The RAID will automatically rebuild, during which access to the
RAID may be slow or non-existent. Remove disk 3 and store it off site.
Week 2: Bring disc 3 back on-site, and exchange with disk 2. The RAID
will rebuild. Take disk 2 off-site. Continue with this, week after week.
If you have a RAID enclosure with nice trays, you won't have to fiddle
with screwdrivers.


A final point about ShadowProtect. ShadowProtect is now back in favor
with me. My new laptop has a UEFI bios, so it took me some time to learn
how to build a recovery USB stick for it, but StorageCraft's support
solved my problems instantly, once I had contacted them via email. The
restore, to the c:\volume only (on this absurdly complex system with
seven partitions for a plain vanilla system), worked well, and I now am
back to my pre-malware state. I have never had this level of consistent
success with any other backup program.



Bill,


Re-assessing: it's not either/or. I can do RAID-1 to the drive inside the
port replicator AND continue to use the external dupe device, manually
implemented, from time to time.


Any thoughts on the following scheme? 1. I dupe the whole internal SSD to
another SSD. 2. I put the main SSD back inside the Thinkpad and the duped
SSD inside the drive bay in the port replicator. 3. Using the disk
utility, I mirror to the duped drive just the C: portion of the original
SSD, I don't mirror the partition labeled SYSTEM_DRV. I just leave it
alone. Seems to me that would protect the second drive's SYSTEM_DRV
partition and still provide a bootable backup of C:, corrupted or
not.


That would protect against a physical failure of the first SSD. The fact
that it cannot protect against data corruption would be handled in the
multiple means I'm already employing.


The cost is close to zero and there's no downside, so why not gain some,
if not total, protection?


--Harry



Hmmm. You make a good
point.  I'll have to think about it. I saw a youtube on Thunderbod
with SSD, and the Mac booted in 12 seconds over it.





Harry, I wouldn't do software
RAID. I am convinced there are problems. Also, if there is a disk
corruption problem, it will simply be duplicated - - on either software
or hardware RAID 1. (It's for that reason that you can run chkdsk on a
RAID 1 volume, but not on a RAID 0, 5, etc.). In the end, I prefer the
system I have, where ShadowProtect does incremental backups every 180
minutes, so I cannot lose more than that. Once I have figured out how to
boot SP's recovery environment on this new computer, I will be happy. I
am about to try a USB stick boot.


I asked an engineer friend of mine at LaCie (now Seagate) if there was a
speed penalty when using a (properly configured) external Tbolt drive as
a boot drive, and he replies, none whatever. This may also be true for
USB 3 - - I have to verify.