Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
On Wed, Dec 28, 2011 at 10:48 AM, Pete Travis wrote: > A 17" laptop cuts an awfully large profile. Are you sure there aren't two > SATA bays? My XPS 17 will have 2 SATA bays. One for the SSD with the OS and the other for a conventional HD with my data.I want to back both of these drives up to an external drive. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
A 17" laptop cuts an awfully large profile. Are you sure there aren't two SATA bays? On Dec 28, 2011 10:27 AM, "linux guy" wrote: > Good discussion. Thanks for the replies. > -- > users mailing list > users@lists.fedoraproject.org > To unsubscribe or change subscription options: > https://admin.fedoraproject.org/mailman/listinfo/users > Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines > Have a question? Ask away: http://ask.fedoraproject.org > -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
Good discussion. Thanks for the replies. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
> How does one set up a "sometimes" RAID ? Or would something like > rsync be better ? What happens the first time I plug my laptop into > the eSATA cable after being away from my desk ? What happens if there > is both new data and an error in existing data ? How does the RAID > software know the difference ? For RAID 1 it doesn't. You want rsync or similar to make backups. > How does one configure the single external eSATA RAID drive to back up > (mirror) the data for both internal drives ? You can get most of the benefit of an SSD (read performance) and set up a RAID 1 with the SSD and part of the hard disk. > > Question 4. > > Can only a portion of the eSATA RAID drive be allocated to the RAID > and the rest left to be mounted by the laptop for general access ? Yes -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
> The overall RAID speed will be limited to the slowest drive. There is some No. On a RAID 1 array read speed is armwavingly the sum of the performance of both drive - actual numbers are a bit more complex because you now effectively have two disk heads on non SSD media cases. > buffering, and the system is not going to be allocating 100% of the CPU to > disk I/O, all the time. But, your max disk read/write throughput will, of > course, be limited to the slowest drive Not always true either but a reasonable approximation for RAID 1. 1 + 0 four disk arrays can give a best of both worlds result in some cases. Alan -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
linux guy writes: I experienced a complete SSD failure this week on my laptop. I've ordered a new Dell XPS 17 laptop which has an eSATA port. I'm sure that Dell appreciates your business. When I had a hard drive fail in one of my laptops, I simply replaced the hard drive. Question 1. How does one set up a "sometimes" RAID ? One does not. RAID is permanent. If one disk fails, the array becomes "degraded". If the failed disk is suitably replaced, RAID resyncs the data onto the replacement, from the remaining working disk. I suppose one can always manually fail a disk, then remove it from the array. Then add it back to the array later. Then, wait a few hours while RAID copies the entire disk. Or would something like rsync be better ? What happens the first time I plug my laptop into the eSATA cable after being away from my desk ? What happens if there is both new data and an error in existing data ? How does the RAID software know the difference ? RAID doesn't care. It duplicates disk blocks. It has no knowledge of the actual data. Whether its extX, xFAT, swap partitions, or something else. It's all just disk blocks, with some jumble of data on them, to RAID. Question 2. Internally, my XPS17 has 2 hard drives. I will probably use an SSD for the OS and a 750 GB 7200 RPM conventional drive for data. How does one configure the single external eSATA RAID drive to back up (mirror) the data for both internal drives ? If you want to set up RAID, when you install Fedora you'll need to choose the custom partition layout. Create identically-sized partitions on both disks, indicating that they're RAID partitions. Then take each pair of partitions, one from each disk, and create a RAID volume on them, then indicate what each volume is formatted as, and where it's mounted, as usual, /, /boot, etc… Question 3. The OS drive will be an SSD which is faster than the eSATA RAID drive, which will probably be a 7200 RPM 2TB+ conventional drive. Will this limit the speed of the SSD to that of the eSATA drive or is buffering employed to allow one to be faster than the other ? The overall RAID speed will be limited to the slowest drive. There is some buffering, and the system is not going to be allocating 100% of the CPU to disk I/O, all the time. But, your max disk read/write throughput will, of course, be limited to the slowest drive, and, for writing, the max write speed gets dictated by the sum total performance of both drives, since each disk block must be written to both drives. Question 4. Can only a portion of the eSATA RAID drive be allocated to the RAID and the rest left to be mounted by the laptop for general access ? Yes. pgpVc3AxPnbp7.pgp Description: PGP signature -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
Am 28.12.2011 05:57, schrieb linux guy: > How does one set up a "sometimes" RAID? what should this be? you have two cases: * RAID * no RAID dinish, this was it only they idea aving "sometimes" a RAID is very strange to say it polite signature.asc Description: OpenPGP digital signature -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
On Wed, Dec 28, 2011 at 5:57 AM, linux guy wrote: > I experienced a complete SSD failure this week on my laptop. > > Question 1. > > How does one set up a "sometimes" RAID ? Or would something like > rsync be better ? What happens the first time I plug my laptop into > the eSATA cable after being away from my desk ? What happens if there > is both new data and an error in existing data ? How does the RAID > software know the difference ? > I do think rsync is the right answer but Raid1 with the eSATA drive as write mostly is a sometimes raid. You will need a big bitmap (to keep track of what is new on the ssd) and I suspect it will steal some performance of your drive even when disconnected. Keywords: Bitmap Write-intent Logging, write-mostly > Question 4. > Can only a portion of the eSATA RAID drive be allocated to the RAID > and the rest left to be mounted by the laptop for general access ? Yes. Partition the drive and set some as filesystem and some as raid. I will give no recipe because you will need to know exactly how this works to use it, and also do an educated guess on the viability of this exotic setup after reading the manual. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
One thing that luckybackup does is send status emails for each backup attempt. That would be really handy for me. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
On Tue, Dec 27, 2011 at 10:43 PM, suvayu ali wrote: > I have never heard of any "sometimes" RAID setup. I don't think that > is possible. I know... it was a longshot. I would say just do incremental backups every night. > There are many tools, rsync being the most commonly used. If you use > LVM, you could also try taking LVM snapshots. I think I'll use luckybackup or something similar. > I personally use rsnapshot, a wrapper around rsync, to back up every > night. So far it has saved me countless times. I like the fact these tools allow one to save a number of snapshots so that if you want to look for something from a month ago, you have a chance of finding it. And they back up without ballooning the storage requirements as time goes on, other than when you have more data on your drive. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Re: Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
On Wed, Dec 28, 2011 at 05:57, linux guy wrote: > Given the nature of the SSD failure I experienced, from now on I wish > to have my laptop running a RAID1 setup via the eSATA port when its > used on my desk. However, when its not used on my desk, I wish it to > function normally without the RAID functionality. I have never heard of any "sometimes" RAID setup. I don't think that is possible. I would say just do incremental backups every night. There are many tools, rsync being the most commonly used. If you use LVM, you could also try taking LVM snapshots. I personally use rsnapshot, a wrapper around rsync, to back up every night. So far it has saved me countless times. GL -- Suvayu Open source is the future. It sets us free. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
Implementing a "sometimes" RAID on a laptop. (eSATA, SSD, RAID 1)
I experienced a complete SSD failure this week on my laptop. I've ordered a new Dell XPS 17 laptop which has an eSATA port. Given the nature of the SSD failure I experienced, from now on I wish to have my laptop running a RAID1 setup via the eSATA port when its used on my desk. However, when its not used on my desk, I wish it to function normally without the RAID functionality. Question 1. How does one set up a "sometimes" RAID ? Or would something like rsync be better ? What happens the first time I plug my laptop into the eSATA cable after being away from my desk ? What happens if there is both new data and an error in existing data ? How does the RAID software know the difference ? Question 2. Internally, my XPS17 has 2 hard drives. I will probably use an SSD for the OS and a 750 GB 7200 RPM conventional drive for data. How does one configure the single external eSATA RAID drive to back up (mirror) the data for both internal drives ? Question 3. The OS drive will be an SSD which is faster than the eSATA RAID drive, which will probably be a 7200 RPM 2TB+ conventional drive. Will this limit the speed of the SSD to that of the eSATA drive or is buffering employed to allow one to be faster than the other ? Question 4. Can only a portion of the eSATA RAID drive be allocated to the RAID and the rest left to be mounted by the laptop for general access ? Thanks ! -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
