[zfs-discuss] zpool on raw disk. Do I need to format?
Folks, I am learning more about zfs storage. It appears, zfs pool can be created on a raw disk. There is no need to create any partitions, etc. on the disk. Does this mean there is no need to run format on a raw disk? I have added a new disk to my system. It shows up as /dev/rdsk/c8t1d0s0. Do I need to format it before I convert it to zfs storage? Or, can I simply use it as: # zfs create MyData /dev/rdsk/c8t1d0s0 Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] zpool on raw disk. Do I need to format?
Awesome. Thank you, CIndy. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] zfs - filesystem versus directory
Thank you all, especially Edward, for the enlightenment. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Legality and the future of zfs...
Folks, As you may have heard, NetApp has a lawsuit against Sun in 2007 (and now carried over to Oracle) for patent infringement with the zfs file system. Now, NetApp is taking a stronger stance and threatening zfs storage suppliers to stop selling zfs-based storage. http://www.theregister.co.uk/2010/07/06/netapp_coraid/?utm_source=feedburnerutm_medium=twitterutm_campaign=Feed%3A+shovelarts+%28Shovel+Arts%29 Given this, I am wondering what you think is the future of zfs as an open source project. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Legality and the future of zfs...
Folks, I would appreciate it if you can create a separate thread for Mac Mini. Back to the original subject. NetApp has deep pockets. A few companies have already backed out of zfs as they cannot afford to go through a lawsuit. I am in a stealth startup company and we rely on zfs for our application. The future of our company, and many other businesses, depends on what happens to zfs. If you are in a similar boat, what actions are you planning? Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Is there any support for bi-directional synchronization in zfs?
Folks, This is probably a very naive question. Is it possible to set zfs for bi-directional synchronization of data across two locations? I am thinking this is almost impossible. Consider two files A and B at two different sites. There are three possible cases that require synchronization: 1. A is changed. B is unchanged. 2. B is changed. A is unchanged. 3. A is changed. B is changed. While it is possible to achieve synchronization for the first two cases, case 3 requires special merging and is almost impossible. I am thinking it is the same problem even at the block level. Even to achieve 1 and 2 is a bit tricky given the latency between the two sites. Is there anything in zfs that makes it easier? Thank you in advance for sharing your thoughts. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] ZFS + WebDAV + AD integration
Folks, I now know that ZFS is capable of preserving AD account sids. I have verified the scenario with CIFS integration. I am now wondering if it is possible to achieve a similar AD integration over WebDAV. Is it possible to retain security permissions on files and folders over WebDAV? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Encryption?
Btw, if you want a commercially supported and maintained product, have you looked at NexentaStor? Regardless of what happens with OpenSolaris, we aren't going anywhere. (Full disclosure: I'm a Nexenta Systems employee. :-) -- Garrett Hi Garrett, I would like to know why you think Nexenta would continue to stay if OpenSolaris goes away. I feel the fate of Nexenta is no different than the fate of my startup company. Both of us are heavily dependent on zfs. And we know OpenSolaris version of zfs is the most stable version. Any business that is dependent on zfs must plan for two things as a contingency: 1. Look for an alternative for zfs 2. Look for an alternative for OpenSolaris Preferably both need to be open source with no licenses attached. Ideally, zfs lawsuit will be put to rest and Oracle will commit for continuing to support OpenSolaris. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] How to identify user-created zfs filesystems?
Folks, In my application, I need to present user-created filesystems. For my test, I created a zfs pool called mypool and two file systems called cifs1 and cifs2. However, when I run zfs list, I see a lot more entries: # zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.31M 1.95G33K /volumes/mypool mypool/cifs11.12M 1.95G 1.12M /volumes/mypool/cifs1 mypool/cifs2 44K 1.95G44K /volumes/mypool/cifs2 syspool 3.58G 4.23G 35.5K legacy syspool/dump 716M 4.23G 716M - syspool/rootfs-nmu-000 1.85G 4.23G 1.36G legacy syspool/rootfs-nmu-001 53.5K 4.23G 1.15G legacy syspool/swap1.03G 5.19G 71.4M - I just need to present cifs1 and cifs2 to the user. Is there a property on the filesystem that I can use to determine user-created filesystems? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How to identify user-created zfs filesystems?
Thank you all for your help. It turns out that I just need to ignore the ones that have their mount points either not defined or are marked as legacy. It is good to learn about history command. Could come in handy. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Raidz - what is stored in parity?
Hi, I am going through understanding the fundamentals of raidz. From the man pages, a raidz configuration of P disks and N parity provides (P-N)*X storage space where X is the size of the disk. For example, if I have 3 disks of 10G each and I configure it with raidz1, I will have 20G of usable storage. In addition, I continue to work even if 1 disk fails. First, I don't understand why parity takes so much space. From what I know about parity, there is typically one parity bit per byte. Therefore, the parity should be taking 1/8 of storage, not 1/3 of storage. What am I missing? Second, if one disk fails, how is my lost data reconstructed? There is no duplicate data as this is not a mirrored configuration. Somehow, there should be enough information in the parity disk to reconstruct the lost data. How is this possible? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Raidz - what is stored in parity?
Hi Eric, Thank you for your help. At least one part is clear now. I still am confused about how the system is still functional after one disk fails. Consider my earlier example of 3 disks zpool configured for raidz-1. To keep it simple let's not consider block sizes. Let's say I send a write value abcdef to the zpool. As the data gets striped, we will have 2 characters per disk. disk1 = ab + some parity info disk2 = cd + some parity info disk3 = ef + some parity info Now, if disk2 fails, I lost cd. How will I ever recover this? The parity info may tell me that something is bad but I don't see how my data will get recovered. The only good thing is that any newer data will now be striped over two disks. Perhaps I am missing some fundamental concept about raidz. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Raidz - what is stored in parity?
Thank you all for your help. It appears my understanding of parity was rather limited. I kept on thinking about parity in memory where the extra bit would be used to ensure that the total of all 9 bits is always even. In case of zfs, the above type of checking is actually moved into checksum. What zfs calls parity is much more than a simple check. No wonder it takes more space. One question though. Marty mentioned that raidz parity is limited to 3. But in my experiment, it seems I can get parity to any level. You create a raidz zpool as: # zpool create mypool raidzx disk1 diskk2 Here, x in raidzx is a numeric value indicating the desired parity. In my experiment, the following command seems to work: # zpool create mypool raidz10 disk1 disk2 ... In my case, it gives an error that I need at least 11 disks (which I don't) but the point is that raidz parity does not seem to be limited to 3. Is this not true? Thank you once again for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Raidz - what is stored in parity?
I am running ZFS file system version 5 on Nexenta. Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Raidz - what is stored in parity?
Thank you, Eric. Your explanation is clear to understand. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] How to obtain vdev information for a zpool?
Folks, When I create a zpool, I get to specify the vdev type - mirror, raidz1, raidz2, etc. How do I get back this information for an existing pool? The status command does not reveal this information: # zpool status mypool When this command is run, I can see the disks in use. However, I don't see my configuration information (raidz, mirror, etc.). Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How to obtain vdev information for a zpool?
Hi James, Appreciate your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Dedup - Does on imply sha256?
Folks, One of the articles on the net says that the following two commands are exactly the same: # zfs set dedup=on tank # zfs set dedup=sha256 tank Essentially, on is just a pseudonym for sha256 and verify is just a pseudonym for sha256,verify. Can someone please confirm if this is true? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Dedup - Does on imply sha256?
Thank you all for your help. It appears it is better to use on instead of sha256. This way, you are letting zfs decide the best option. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Possible to save custom properties on a zfs file system?
Thank you all for your help. Can properties be set on file systems as well as pools? When I try zpool set command with a local property, I can an error invalid property. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] What is l2cache setting?
Folks, While going through zpool source code, I see a configuration option called l2cache. What is this option for? It doesn't seem to be documented. Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] What is l2cache setting?
Neil, Thank you for your help. However, I don't see anything about l2cache under Cache devices man pages. To be clear, there are two different vdev types defined in zfs source code - cache and l2cache. I am familiar with cache devices. I am curious about l2cache devices. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Feature differences between Solaris 10 9/10 and build 147
Folks, Here is the list of ZFS enhancements as mentioned for the latest Solaris 10 update: * ZFS device replacement enhancements - namely autoexpand * some changes to the zpool list command * Holding ZFS snapshots * Triple parity RAID-Z (raidz3) * The logbias property * Log device removal - at last * ZFS storage pool recovery * New ZFS system process – In this release, each storage pool has an associated process, zpool-poolname * Splitting a mirrored ZFS storage pool (zpool split) I am wondering if any of these enhancements are not available under build 147. Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Dedup relationship between pool and filesystem
Folks, I am a bit confused on the dedup relationship between the filesystem and its pool. The dedup property is set on a filesystem, not on the pool. However, the dedup ratio is reported on the pool and not on the filesystem. Why is it this way? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] What is dedupditto property on zpool?
Folks, One of the zpool properties that is reported is dedupditto. However, there is no documentation available, either in man pages or anywhere else on the Internet. What exactly is this property? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Any zfs fault injection tools?
Folks, Command zpool status reports disk status that includes read errors, write errors, and checksum errors. These values have always been 0 in our test environment. Is there any tool out there that can corrupt the state? At the very least, we should be able to write to the disk directly and mess up the checksum. Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Any zfs fault injection tools?
Freddie, Thank you very much for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] When is it okay to turn off the verify option.
Folks, As I understand, the hash generated by sha256 is almost guaranteed not to collide. I am thinking it is okay to turn off verify property on the zpool. However, if there is indeed a collision, we lose data. Scrub cannot recover such lost data. I am wondering in real life when is it okay to turn off verify option? I guess for storing business critical data (HR, finance, etc.), you cannot afford to turn this option off. Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Optimal raidz3 configuration
Folks, If I have 20 disks to build a raidz3 pool, do I create one big raidz vdev or do I create multiple raidz3 vdevs? Is there any advantage of having multiple raidz3 vdevs in a single pool? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] How does dedup work over iSCSI?
Folks, Let's say I have a volume being shared over iSCSI. The dedup has been turned on. Let's say I copy the same file twice under different names at the initiator end. Let's say each file ends up taking 5 blocks. For dedupe to work, each block for a file must match the corresponding block from the other file. Essentially, each pair of block being compared must have the same start location into the actual data. For a shared filesystem, ZFS may internally ensure that the block starts match. However, over iSCSI, the initiator does not even know about the whole block mechanism that zfs has. It is just sending raw bytes to the target. This makes me wonder if dedup actually works over iSCSI. Can someone please enlighten me on what I am missing? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How does dedup work over iSCSI?
Hi Neil, if the file offset does not match, the chances that the checksum would match, especially sha256, is almost 0. May be I am missing something. Let's say I have a file that contains 11 letters - ABCDEFGHIJK. Let's say the block size is 5. For the first file, the block contents are ABCDE, FGHIJ, and K. For the second file, let's say the blocks are ABCD, EFGHI, and JK. The chance that any checksum would match is very less. The chance that any checksum+verify would match is even less. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Any limit on pool hierarchy?
Folks, From zfs documentation, it appears that a vdev can be built from more vdevs. That is, a raidz vdev can be built across a bunch of mirrored vdevs, and a mirror can be built across a few raidz vdevs. Is my understanding correct? Also, is there a limit on the depth of a vdev? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] How to create a checkpoint?
Folks, My understanding is that there is a way to create a zfs checkpoint before doing any system upgrade or installing a new software. If there is a problem, one can simply rollback to the stable checkpoint. I am familiar with snapshots and clones. However, I am not clear on how to manage checkpoints. I would appreciate your help in how I can create, destroy and roll back to a checkpoint, and how I can list all the checkpoints. Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How to create a checkpoint?
Thank you all for your help. Looks like beadm is the utility I was looking for. When I run beadm list, it gives me the complete list and indicates which one is currently active. It doesn't tell me which one is the default boot. Can I assume that whatever is active is also the default? Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] How to grow root vdevs?
Folks, I am trying to understand if there is a way to increase the capacity of a root-vdev. After reading zpool man pages, the following is what I understand: 1. If you add a new disk by using zpool add, this disk gets added as a new root-vdev. The existing root-vdevs are not changed. 2. You can also add a new disk by using zpool attach on any existing disk of the pool. However, the existing disk cannot be part of a raidz vdev. Also, if the existing disk is part of a mirror, all we are doing is increasing redundancy but not growing the capacity of the vdev. The only option to grow a root-vdev seems to be to use zpool replace and replace an existing disk with a bigger disk. Is my understanding correct? Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How to grow root vdevs?
Thank you for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] How to safely parse zpool get all output?
Folks, Command zpool get all poolName does not provide any option to generate parsable output. The returned output contains 4 fields - name, property, value and source. These fields seems to be separated by spaces. I am wondering if it is safe to assume that there are no spaces in the field values. If this is the case, I can split the output across spaces. Thank you in advance for your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How to safely parse zpool get all output?
Hi, Thank you for your help. I actually had the script working. However, I just wanted to make sure that spaces are not permitted within the field value itself. Otherwise, the regular expression would break. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] (Fletcher+Verification) versus (Sha256+No Verification)
Folks, I have been told that the checksum value returned by Sha256 is almost guaranteed to be unique. In fact, if Sha256 fails in some case, we have a bigger problem such as memory corruption, etc. Essentially, adding verification to sha256 is an overkill. Perhaps (Sha256+NoVerification) would work 99.99% of the time. But (Fletcher+Verification) would work 100% of the time. Which one of the two is a better deduplication strategy? If we do not use verification with Sha256, what is the worst case scenario? Is it just more disk space occupied (because of failure to detect duplicate blocks) or there is a chance of actual data corruption (because two blocks were assumed to be duplicate although they are not)? Or, if I go with (Sha256+Verification), how much is the overhead of verification on the overall process? If I do go with verification, it seems (Fletcher+Verification) is more efficient than (Sha256+Verification). And both are 100% accurate in detecting duplicate blocks. Thank you in advance for your help. Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] (Fletcher+Verification) versus (Sha256+No Verification)
Thank you all for your help. I am the OP. I haven't looked at the link that talks about the probability of collision. Intuitively, I still wonder how the chances of collision can be so low. We are reducing a 4K block to just 256 bits. If the chances of collision are so low, *theoretically* it is possible to reconstruct the original block from the 256-bit signature by using a simple lookup. Essentially, we would now have world's best compression algorithm irrespective of whether the data is text or binary. This is hard to digest. Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] How to increase iometer reading?
Hello, We are building a zfs-based storage system with generic but high-quality components. We would like to test the new system under various loads. If we find that the iometer reading has started to reduce under certain loads, I am wondering what performance counters we should look for to identify the bottlenecks. Don't want to replace a component just to find that there was no improvement in iometer reading. Thank you in advance for your insight. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] (Fletcher+Verification) versus (Sha256+No Verification)
Ed, Thank you for sharing the calculations. In lay terms, for Sha256, how many blocks of data would be needed to have one collision? Assuming each block is 4K is size, we probably can calculate the final data size beyond which the collision may occur. This would enable us to make the following statement: With Sha256, you need verification to be turned on only if you are dealing with more than xxxT of data. Also, another related question. Why 256 bits was chosen and not 128 bits or 512 bits? I guess Sha512 may be an overkill. In your formula, how many blocks of data would be needed to have one collision using Sha128? Appreciate your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] (Fletcher+Verification) versus (Sha256+No Verification)
I am posting this once again as my previous post went into the middle of the thread and may go unnoticed. Ed, Thank you for sharing the calculations. In lay terms, for Sha256, how many blocks of data would be needed to have one collision? Assuming each block is 4K is size, we probably can calculate the final data size beyond which the collision may occur. This would enable us to make the following statement: With Sha256, you need verification to be turned on only if you are dealing with more than xxxT of data. Also, another related question. Why 256 bits was chosen and not 128 bits or 512 bits? I guess Sha512 may be an overkill. In your formula, how many blocks of data would be needed to have one collision using Sha128? Appreciate your help. Regards, Peter -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
